I found this guy CarBo0n in a duel room, and u can see how he is using UC on the replay and i also have a screenshot of him asking how he turns his UC off.
http://speedy.sh/GaWMU/DUEL-Trench-20120518-122617.gzr Replay
http://tinypic.com/view.php?pic=do0xll&s=6 Screenshot