Instanced Materials on ZBrush Models

I have ZBrush and 3DS Max and I want to make multiple material slots so I can do something simple like change the skin color of the character, or change armor color. ZBrush exports 1 mesh, 1 texture so I am left hand painting the model any time I want to make a change. What am I missing?? I was thinking use polygroups in ZBrush but those are big strokes and I am pretty sure I would lose all shading capabilities.