Use magos and take a look at the dragonspawn texture, it's a bit of a pain to even attempt to skin because it's done unlike any other skin in wc3. Idk why, but that explains the lack dragonspawn skins (trust me, I'd like some skins of that model too).
Though a simple color shift may be pretty easy to do
Great model but it needs reduced filesize ;/ Maybe u should remove custom animations? Let all guys use this model, distribute it on public! Anyways I will +rep u again (now I must "spread some repuation around" before i give it to u again ...) cause your really helpful