Okay, Poser 7 does not have gamma correction built in so leave the VSSProp settings for gamma as is.  Now the VSS lights packaged with the prop happen to be too bright.  BB admits that he incorrectly created them.  The IBL intensity as well as the Infinity Light intensity must be turned down drastically to give you acceptable skin tones in the renders.  If you haven't perused the other VSS thread yet, do so.  It does contain reams of information and tips.  Follow the link:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2737823&page=1