I suck at writing instructions.. or anything for that matter.. but lets see what I can do to get them to work for you:
Firstly, unless your using 40d11 you'll have to open each of the sprite sheets in paint or something similar and manually convert them to .bmp files via save as (Since .png support was only introduced in 40d11 and any version prior wont recognise them).
Secondly if your using a graphics pack thats not the DFG (MikeMayday pack) youll have to find the "graphics.txt" file in the raw/graphics folder in DF (It may have different names depending on the set you were using, which MAY consist of several .txt files) and find the relevant entry positions in those files for the text under each sprite sheet in the first post (Note: you'll also have to change the line from [FILE:mayday/dorfs.png] to[FILE:mayday/dorfs.bmp] if you had to convert them to .bmp files due to another version pre-40d11)
Thirdly it "SHOULD" work.. But it is late and I am stupidly tired so I might have missed something. If your still having problems post here and I'll check back in the morning.
Writing the text files and compiling it I'm kind of putting off since I HATE doing that stuff
To Solifuge: Hopefully there wont be too much confusion.. since I am only going to use the animal masks for military and mabey some rare nobles. I dont really plan on making an olm/frog/swallow mask and eventually I plan to get around to doing the other sprites for animals so I'll make sure there is a visible difference. But thats way down the bottom of my list ATM
... but technically I am like.. umm.... almost 4/5ths of the way through the vanilla races! WHEEE!
To Vactor: You call him Pot on head.. I call him possible cook!
To Johnnybeltz: Keep forgetting to reply... Your set's looking great, only suggestion I'd make would be to change the pure black outline your using, since the DF background colour is pure black anyway (unless its "flickering" or dworning?) It doesnt really do that much. But If you use a darker grey instead you'll still get that nice outline youve got going and it will show up everywhere! Keep it up! (And dont worry about changing your thread name doesnt bother me)