It sounds like a really good idea with lots of potential, but there's a few things you'll need to do to generate some interest to make people become involved with it.
Firstly, you need to announce prizes. People respond to incentives, and prizes (especially if they involve cash) is a big one. If you are able to get enough people to participate, I'm sure Errant and TGC will throw in a few guns/model packs and other generous forum members would contribute various sounds, entities, models and segments.
Secondly, you need to construct a professional, informative thread which contains all information, including pictures of the maps and possibly links to videos of the map, a list of prizes, current teams and participants, and details on the actual tournament itself (when it will occur and under which timezone).
Good luck with this. If you don't do any of the above, this tournament will crash and burn. I hope it doesn't, because it sounds like it could be a lot of fun.
[b]FPSC MIGRATION: http://forum.thegamecreators.com/?m=forum_view&t=142497&b=21