Found it! Reposted below for my own reference.
: Build an optimized ranged combat character using nothing but the PHB and DMG.
: Tier 3. No game breaking abilities, dies if stupid, but has a few tricks to keep things interesting.
: Ranged Weapon Combat, Two Weapon Fighting, Stealth, Reflex and Will Saves, Concealment Bonuses
: Will Saves, Rogue Skills (unless investing high Int in stats), Social Encounters
Race: Human
This is a feat heavy build and the extra first level feat helps.
Alignment: Any Evil
Stats: At least 16 in Dexterity, at least 12 in Intelligence. Put points into Dexterity.
Level 1: Rogue
Feat: Point Blank Shot
Feat: Precise Shot
Skills: 4 ranks in each of the following: Disguise, Hide, Move Silently, Perform (Dance). The remaining points may be spent as you wish. I personally like Disable Device, Listen, Search, Spot, Tumble and Use Magic Device.
At this level you are ready to start using a bow. Focus on engaging enemies from midrange and supporting your allies. You should often win initiative due to your high Dex mod, so take advantage of any flat-footed enemies to add sneak attack on your ranged shots when within 30 ft. Due to low hit points, this extra damage should knock most enemies out in one shot unless they're immune to critical hits (like undead). Your primary weapon will be a shortbow. A light crossbow would deal more damage but you'd need to spend a move action to reload, and you want to keep your squishy d6 hit points out of melee if you can avoid it. If your weight limit allows it, carry a sling as a backup weapon to give you the option of dealing bludgeoning damage to skeletons from range in order to bypass DR.
Level 2: Fighter
Feat: Rapid Shot
Skills: Put 2 cross-class ranks into Perform (Dance). The remaining points may be spent as you wish. I personally like Craft (Poisonmaking) since it's a class skill and there's little else worth taking here.
At this level you're finally at +1 BAB, so you can draw a weapon during a move action. You also gain a decent buffer to your hit points with that d10 unless you roll poorly. Your focus should be on obtaining a masterwork composite longbow with a strength rating to allow you to add your Str mod to damage. You're now proficient in all armour but I recommend sticking with light. Your Dex mod means most medium or heavy simply isn't worth the additional AC for the cost of movement penalty, especially when you're moving tactically to avoid enemies benefiting from soft cover. Obtaining armour spikes means you'll threaten your surrounding squares even when holding a bow, so I'd recommend investing in these if you can afford the extra weight. With Rapid Shot you'll want to take the -2 penalty to hit for the extra attack in every situation except where you need a roll of 18 or higher to hit the enemy without the penalty.
Level 3: Fighter
Feat: Dodge
Feat: Mobility
Skills: There's nothing you should need right now. Spend the remaining points as you wish. I personally like to max my Craft (Poisonmaking) here.
At this level you're picking up the prerequisites for later prestige classes, and there's little that's different in your playstyle. Your extra hit points give you a solid buffer for combat unless you've had terrible rolls. In terms of equipment, start saving for a Handy Haversack to carry your loot and ammunition. You want to avoid being burdened with a medium load if you can help it.
Level 4: Ranger
+1 Dex
Skills: 2 ranks in Hide and Move Silently, 4 ranks in Knowledge (Geography)
Ranger opens up some nice tricks, beginning with wand use. You should probably be able to afford a wand of Cure Light Wounds by now unless you're still saving for your haversack. Keep one in your pocket and you can use it without making a UMD check, since the spell is now on your class list. The same applies for other nice spells such as Resist Energy, Barkskin or Freedom of Movement, but you're not going to be able to afford a huge number of wands so make the Cure Light Wounds your first priority. Everyone will need healing sooner or later and it's nice to have a way to keep yourself alive that doesn't require instant access to a Cleric. For your Favored Enemy there's a heap of choices, but personally I go with Undead. You tend to see these guys at every level of play and your sneak attack doesn't work on them, so the extra damage is nice.
Level 5: Ranger
Feat: Two Weapon Fighting
Skills: 2 ranks in Hide and Move Silently, 4 ranks in Knowledge (Geography)
Why did we pick Two Weapon Fighting for our bonus combat feat here? Because even if you focus on ranged combat you should still have a melee option. I'd try to get a hold of a masterwork greatsword now for melee needs since you've probably got your haversack and can afford the extra weight. With a greatsword as your main attack and armour spikes as your off-hand attack, you can deal a 2d6 and a 1d6 at -2 to hit. Get flanking to add 1d6 sneak attack to each of these as well.
Level 6: Assassin
Feat: Combat Reflexes
Skills: Nothing is essential until next level. Take the opportunity to top up your Rogue skill ranks (5 in Disable Device and 1 in Tumble for example)
Don't forget to go murder someone before you take this level. Since you're an adventurer, I'm sure you've already got a trail of bodies into the double digits so this shouldn't be too hard. You get a couple of nifty class features here. Another sneak attack d6 is good. The death attack is very weak but not bad as a freebie. I once used it to murder a sleeping Paladin so that he couldn't be brought back to life with a Raise Dead spell. Don't expect to use it frequently though. By far the nicest feature is access to the Assassin spell list, though you can only pick two spells to know and cast only one per day. Remember, any spell on your list is fair game for wand activation.
Level 7: Assassin
Skills: 2 ranks in Hide. The remaining points may be spent as you wish.
You get another spell per day and another known spell, plus a boost to BAB. Uncanny Dodge is good, though it's uncommon with your Dex mod that you'll be flat-footed too often. Not much changes at this point in terms of combat tactics. Rapid Shot if you get the chance, or Two Weapon Fighting if you have to melee. By now you can start looking for a few extra useful items such as +1 weapons and armor, arrows of various metals to break DR types, a few utility wands for useful common buffs and potions for the rare ones.
Level 8: Shadowdancer
+1 Dex
Skills: You no longer have any skill prerequisites for prestige classes, so use your best judgement from here on out.
Hide in Plain Sight. You are now a stealth monster. There is no situation where you don't want to use this in combat. Go ahead and move at full speed and just eat the penalty. You still have a chance to hide if you roll well and your opponent rolls poorly. The wording of the special ability is ridiculous as it's so open to interpretation. As written, you can hide in your opponent's own shadow so long as they're no more than 10 feet away. Combine with sneak attack for more awesome. When using ranged combat, remember you are still limited by the rules for sniping while hiding.
Level 9: Shadowdancer
Feat: Endurance
Evasion, Darkvision, and Improved Uncanny Dodge, plus you finally get your +6 BAB, meaning you now have a second attack. Shoot stuff in the dark and if they can't see you you're effectively invisible. Sadly it's only 60 ft. which means most other stuff with Darkvision can see you just fine. Your Hide in Plain Sight should still give you a chance to avoid these spotting you though.
Level 10: Horizon Walker
Oh wait, that 60 ft. Darkvision? It's now 120 ft. Shoot stuff at full range increment in pitch black. Virtually nothing in the Monster Manual can see you this far away. Your only problems will be line of sight and cover penalties.
Level 11: Shadowdancer
You get a pet Shadow. As a combat ally these guys are best used against anything that doesn't have magic weapons or spells, since your companion is fairly squishy against a decent sized fireball. Their true strength however lies in their out of combat utility. As ethereal creatures they can pass directly through solid objects. Scouting becomes a matter of instructing your Shadow to check what's inside the next room. Get your Shadow to look inside that suspiciously large chest to see if it's actually a Mimic. The once per day illusion is also a fun open ended trick up your sleeve. This is the level that rewards imagination.
Level 12: Shadowdancer
+1 Dex
Feat: Improved Two Weapon Fighting OR Manyshot
This is your last Shadowdancer level. You pick up an escape button in the shape of a short teleport. Past this point this prestige isn't worth continuing with, but Shadow Jump can save your life if you're in a tight spot. Feat choice is up to your personal play style. If you like being mobile, Manyshot is good for shoot and scoot. If you like stabbing things in melee, you may get more mileage out of Improved Two Weapon Fighting. At this stage you have a +8 BAB and +9 Fort/+12 Reflex/+1 Will saves from your classes.
Level 13-17: Assassin
Feat: Improved Two Weapon Fighting OR Manyshot
More sneak attack, more spells, more rogue skills if you need them. Level 15 is the chance to pick up the feat you missed at level 12. There's nothing spectacular about these levels except the new spells you learn and the bonuses to sneak attack.
Level 18-20: Eldritch Knight
Feat: Improved Precise Shot
Feat: Greater Two Weapon Fighting
Your spells from Assassin qualify you to take this prestige. The benefit for taking it is an extra feat, +1 BAB and +2 Will saves at the cost of 1 caster level, 1d6 sneak attack and fewer skills. You can really go either way here but personally I like Eldritch Knight simply for the fact I now have seven different classes on this character.
Final Notes: An interesting alternative feat for this build is to use Quick Draw and go the route of throwing splash weapons such as acid flasks. While fun, this isn't the focus of this build, and it would likely have to sacrifice either Greater Two Weapon Fighting or Manyshot to accomplish this, both of which are great feats. You can pick up Improved Precise Shot or Greater Two Weapon Fighting as early as 15th level by taking your first level of Eldritch Knight here instead of at level 18 and using the bonus feat, but ultimately you end up slowing down your spell progression and sneak attack increases doing this.