@mathijs yeah 2v2, and hopefully bigger ones in the future? On the note of not turning up - obviously that is an outcome but there is the possibility that the better players will help their partners(it would be in their best interests?)
@ict yup quite a few, really it depends on whether or not you'll want to do this kind of thing more than once - I guess there are three problems, getting people to sign up, getting people paired into teams and finally recording who wins/loses. My answer to all three would be dependant on whether or not this would be something you guys would be interested in doing more than once.
As for getting people to sign up, it would be possible to advertise the event when bfme loads (and in lobbies?). The second two problems are really one, it wouldn't be terribly difficult to make something that would handle both but for a one off event it would be pretty pointless so using other online resources is probably the best plan of action - for the first time round anyway. After the first time, you can atleast gauge how popular it is.
Overall, what's life without a little risk? People might not sign up, turn up, be nice who knows? I'd like to guess that it would be the opposite though, and people will help others out.