All the information is here:
http://forum.sa-mp.co.uk/index.php/topic,3874.0.htmlI'll just give you guys the lowdown right here if you can't be bothered reading all that.
-4 players per clan
-Players are lined up against 4 other players from a different clan and duel (hence the tournament is more about the strengths of individual players rather than their work as a team, like most clanwars are)
-Fights must be 4shot (sawns + uzis/tecs), and the switch bug is allowed.
I know that'll be a bitch for those of you new (last year or so) to LWs, but if you're up for a challenge then you may as well sign up.
Read the link for full details.