I've never done it before, but if I had to guess how, I'd probably get the source picture, draw a white part on a new layer for the mask, and use the brush techniques in the tutorial to get the eyes and lips drawn. Then, I'd duplicate the layer with the friend's picture, make it the alpha mask, and the makeup part should form over the face and give it a facepaint look.
Displacement and Alpha Mask pluggin:
viewtopic.php?f=16&t=24491
Faking Soft Brushes and Burn/Dodge/Blur Tutorial:
viewtopic.php?f=15&t=22096