you would think it is that simple, wouldn't you?
but the whole point of this is to create/access a second set of UV coordinates!
example:
Skin 1, UV set 1, diffuse texture
Skin 2, UV set 2, shadow texture (lightmap)
this way you can use a different UV mapping for each of the both skins!
And THAT is the hard part! Perhaps I did not get it, but I don't think you can modify the UV coordinates for each skin seperately using C-script!
JCL said that the engine internally supports 3 different UV sets, but you can only access one with MED!