by frag.machine » Fri Sep 19, 2008 12:09 am
Not sure if this is exactly what you want, but you can open the player.mdl in any editor (QME, Quark 4.07, etc) export the skin to a .pcx file and then extract the color palette with your favorite painting tool and use it to paint your own. Colors with index between 16 to 31 inclusive are for shirts, 96 to 111 are for pants.
I know FrikaC made a cgi-bin version of the quakec interpreter once and wrote part of his website in QuakeC 
(LordHavoc)