i'm not totally confident of the rules, but i know the general idea is to reflect real life treaties, so u can make a binding treaty e.g.treaty never to attack each other, and u can't break it. if u do u lose.

how does these treaties get enforced?

I'm in, tell me who is with who. Italy?

Yeah, I think I'll join if one's made.

There's some guy that always organizes them though... he's got a good system worked out

I am in such a contract game at the moment. It is great fun, although I will be defeated soon. I would also be interested in playing another one, this time with more success. The guy organizing them is PaulSalomon27.
There have been some violations of the contracts, but all of these cases have been settled by mutual agreement. So to play such a game you have to be willing to stick to what the global court decides.
Otherwise the rules are simple. Contracts are proposed and if both parties agree, they are send back and forth with square brackets around, like [England will not move to MAO through Fall 1903, and France will not attack Britain through Spring 1906], for instance. Most contracts are valid only a certain period of time. Otherwise you can lie, mislead, stab, and so on just as in usual games, you just have to follow your contracts.