first of all:
Your Character needs to be created out of different models
Means 1 model for hair, one for body, one for armory..etc
Now you can play with the ent.red/green/blue values, and ent_morph. That´s the easiest way.
Better way: a shader wich changes the textur hue by using ent.skillXX-ZZ as rgb values for skillAA as Skin_id