I think you would still need trans maps for it to look right but a linear texture should be fairly easy.

baggins bill did do a hair setup that could use a gray scale map that could be changed to any color and would shine like hair....

thread:
Attempt at reducing Koz hair speculars in P6
http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2660693&ebot_calc_page#message_2660693

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