Hi Sunflash,
Skinning the models in FPSC was a little different than usual, because I was using a Normal map shader. Heres how I would create a skin for a character model, known as a diffuse texture.
I use Adobe photoshop and build up the skin in layers. First I paint the entire texture in greyscale, using light and shade and adding in detail. Then I use layer combinations of photographic textures using different blend modes (overlay, screen, multiply etc) to get the colour.
For final lighting, I light the model in 3ds Max and then use render to texture to create the final skin.
If I've been using a Normal map for bump detail, I miss out the first step and just paint the diffuse map using colours with no shading. This creates the XXXX_D.tga (Diffuse texture without shading) textures.
To create the XXXX_D2.tga (diffuse texture with shading) textures I simply render a lit model model with the normal map applied.
Some resources that I found useful once:
http://www.planetquake.com/skindom/tutorials
and
http://www.polycount.com
