Yep thats a tough one!!

You can use fur which does have cool results if you have the time to sit and render tests and paint your baldness, direction and inclination maps in photoshop.

We found that doing them as a map on a poly surface is good enough providing you do them right. I suggest you get a digital camera and take lots of close up photos and mask them out in photoshop, it will save you painting them by hand.