set some kind of check sum on the models , a good fast way is read a few bytes out of the texture after you lock it and multiply it by the prim so it makes a unique value then you can pick out different textures at will.
or use prims on their own or take it off the stack ..etc etc etc its basically what method you prefare
what i do is usualy grab a few bytes from the actual texture somewhere in the first block , it usually gives you a very good way of distinguishing against other textures and you can cham , skin , color whatever one you want..
most new game programmers have become lazy and draw all active models ie players bullets guns in the same stride and tell the engine to distinguish , so strides in the latest games are a bit useless as a way in general but basically its entirely up to you which method you chose , you could use shaders as well if your card supports it but them who's cards dont it wont work for.