Ok, I went and found the post where we talked about this before: It's in this thread where we sort of rambled all over the place but the basics are there including a link to a tutorial by RoofMonkey. The posts about the skintone changer, CL tool and changing skins with SimPE start on page 2. Provides a bit more useful info.
http://www.sunsims.com/forums/showthread.php?t=627