I'm working on this myself. I believe you base it off of the texture map for the head. In the areas that have the eyebrows you paint white brow lashes on a black background. Same with the eyelashes. Then save the blackground whith the lashes texture map as a transmap. My advise ( since I'm working on it myself and haven't made one yet although I've done it for Posette) is to download a Stephanie texture and see how that's done. The Stephanie texture by Thumper in the free stuff has a transmap for the lashes. It's gotta be similar for the brows. Hope this helps..a little.