Zbrush hair is already mapped.. the strands encompass the entire uv space, and run vertically. The taper of the fibers handles the taper of the texture.

The trick seems to be to use more polys then you'd think you'd want to use. And you can even export groomed "morphs" of the fibers.. ;)

Mec4d (Cath) has been pioneering its use in poser, and has some youtube video tests of the progress.

 

Way too many people take way too many things way too seriously.