i KNOW there is a great tutorial out there, but i cannot find it right now...
but i think the essence is something like that...
www.paultosca.com/varga_hair.html
maybe i can find it....
FOUND it.
www.art-collaborations.com/Valea_HexHair.pdf

hope that helps, only read it once to get a vague theory... and there are sure way more ways :)