Ahh, I suspected you meant something like that...
I have an (EVER ONGOING! lol) WIP along the same lines:
http://www.coolminiornot.com/forums/viewthread.php?tid=17510
I suggest first basecoating your figure and then dampening it with water, and taking a photo with a flash at the angle you want the light shining in order to see where the highlights and shadows are.
EDIT: Looking at my old WIP, the pics don\'t seem to be working, so I\'ll see if I have one to add now...
EDIT: Here you - This is as far as I got before I got side-tracked