hmm... maybe... it depends... I'm not sure if the peds have all the animations that you'd need. like jumping... or shooting.
You can try though.
I suggest using one of the gang skins if you're gonna try it.
EDIT: I just remembered... MTA is supposed to use the gang skins... (it doesn't, but it should). If they've managed to get those things working, then yes, you should be able to change your player model.