I am very clueless on render passes in general and for the most part plan to just render things in 1 or 2 passes but I haven't been able to find much good information on rendering hair in a separate pass.

Basically I want to be able to render my entire scene minus the hair (shave and haircut) using mental ray and then in a separate pass render just the hair using maya software. Does anybody know how to go about doing this?