I do not have ZBrush or other fancy tools or bump sets so for my Roxie dooldes I will have to live with what's there for Roxie, Poser and PaintShopPro.

To avoid local skin color(lightness) affecting bump I was thinking of using the current plain desaturated map and get the difference with a blurred version of same, with blur radius on the order twice the size of skin detail. The blurred area should have the average skin lightness and the difference be representative for the bumps relative to average skin level.