You can edit your uv in any art program, however first you have to make it, and this can be a difficult process.
I'll try to see if I can find a tutorial for gmax but your probably better off looking for yourself
To save your skin on your unit, you have to create a path for it. Obviously I don't know a lot about the modeling part of uv wraps...probably better off asking in the modeling, but Sansui might help you.