I have trained speardwarves, spearmen, pikemen, and speargoblins successfully with a minimum of training deaths, and I train them the same way as any other military dwarf.
You need to train your dwarves to legendary in wrestling first, and then you need to outfit them in full plate armor before they even touch a weapon. Once they're at that point, it doesn't really matter the quality of the weapon you give them, but if you're worried, you can give them basic quality silver weapons.
Higher quality weapons are always better because the quality of a weapon affects the chance to hit in combat and to
not hit while sparing. So give them exceptional or masterwork silver spears, but otherwise your advice is pretty much spot on.
1. Legendary wrestler before any armor.
2. Outfit with exceptional or masterwork steel armor(plate over chain) and shield + mace or war hammer(bronze, bismuth bronze, copper, silver from about worst to best)
3. Legendary Macedwarf, Hammerdwarf, Shield user and Armor user (last one is optional really)
4. Train spears(exceptional or masterwork silver)
I have never had a sparing death out of 2 dozen speardwarfs in my last 3 forts when I follow the above. Also, be sure you put anyone who isn't a steel plate+chain+shield multi-legendary on patrol or give them crossbows else you will have casualties.
Also, the spears used in DF seem to be short spears such that dwarfs can use shields with them(mine seem to anyway).