here are two  tutorial how to get rid of highlights in skin textures .and also shadows. its for photoshop.

if you have a good quality picture then you should be able to get  90% diffuse skin

unsharpmasked.com/blog/2008/08/photoshop-high-pass-filter-removing-wrinkles-in-fabric-part-2/
www.ten24.info/oldman/vid_SpecRemoval.htm