I think you mean skinning in 3dsmax ie. the uv maps. Most new models use the same uv maps as the model they were based on so you just edit the texture file for the model it was based on. You can find which textures are assigned to each model in desc_model_battle. If you want to learn how to do uv maps in 3dsmax then I suggest looking in the tutorials section. If you modelled the unit yourself I would presume you know what the uv map is.