How to add skins to bodygroup

How exactly do you add different textures to a model to be changed with the body group tool. (or a different tool) Kind of like how the citizens with suits can change theirs.

You just take the part of the model you want to have as the bodygroup (in a seaparate version of the model file in your modelling program prefereably) and remove everything else (if you already have your bodygroup made ignore the first bit), apply the alternate skin to the bodygroup model and export, compile as you would a bodygroup normally, but generally will be in the same bodygroup as the original skin version (so you can switch between them).