In fall 1999, Amy Swift '00 and i threw a SWIL all-campus dance party. There was precedent for this event (someone threw one in the mid-1990s), but it is by no means a tradition. However, should you decide to do such a thing, you'll need to do some basic all-campus-event-related things.
First of all, like any other event, you should get help running it. The biggest part of this is convincing SWIL at large to come beforehand to help set up, and to stay afterwards to help clean. This is very important -- parties are messy.