You can use the default in game MP options but I'd suggest Qtracker.
It's a nifty piece of software that tracks ALL of your games. It also includes some cool features like if the server you wish to join is full, you can set it to automatically join once someone leaves and there is an opening. You can get it here
i've been tryin to find a multiplayer game of jk for years aswell i was one of the best apprantly lol anyway i was hoping when i got the game installed i was hopin to whoop some pro's butt but i just found out there no servers anymore so i was like -gasp- and the only one i found don't even work so i think i'm screwed