My school is a dry campus and last year IFC imposed new rules on fraternity rush. Since we don't have houses on campus, the fraternities could technically have alcohol at their events...that is until last year. Now, not only can they not hold events with alcohol, but they can't go to an establishment that makes a certain percentage of their proceeds (40% I think) from the sales of alcohol.
The key to having successful dry events is to keep people occupied. You need to have things going on so that they don't feel that they need to have the alcohol in order for them to have fun while at your house. One of the fraternities rented one of those air joust things, another held a luau and had a slip and slid out across the lawn. People are interested in things that are fun, but too often they think that they can't have fun without the alcohol....you just have to prove them wrong!
Good luck!!