Well, I don't know about an actual omni-drive that uses omni-wheels (since an omni-wheel can only be powered in one direction of motion but move in two it gets confusing I suppose), but my team was designing a ball drive - a drive that has a ball at each corner that can move in two directions (left/right or up/down). Code can be found in this thread:
http://www.chiefdelphi.com/forums/sh...ad.php?t=43301