Sometimes a Poser texture comes with a "specular" texture map in addition to the colour and bump maps. This can be used for the variable highlights. In fact, I think it may be a good thing to make one anyway, if it's missing (e.g a version of the bump map with higher (or lower) contrast or something).
If you want a "partially wet" look for something (a road after rain, Vicky after having a shower etc.), you can also make a separate reflection map to be used with "variable reflections".
Lars "bigbraader".