Take them into a modeling or UV app and assign everything to one material to clear out all that bad export practice junk. Then, start remapping material zones. You won't find an easier way. By the time you figure it all out, you could have already remapped it. :)

UVMapper lite can let you easily map everything to one material. IF the UV isn't crap, which I suspect it probably is, you could even remap it from there. But, you'll probably end up seeing a complete garbaged UV when you load it, so don't even think about it. :)

I'd load the thing up in my most lightweight modeler, remap all the material zones, then, dump it back out. If you need a good UV map for it, the remap the UV first, of course. Free modelers would be easier than using Poser for this. Wings3D, Anim8tor, Blender, etc. Some other free UV programs might work too, with less clutter you won't be using, like Roadkill.