A holonomic robot uses omni-directional wheels to drive and turn in any direction. The wheels must be aligned to the center of the robot. I am using Connexion's Space Navigator to proportionally remote control the robot. The Space Navigator button toggles between the absolute and relative control mode. In the absolute mode the forward direction of the Space Navigator is mapped to north direction of the robot. Using the compass sensor, the robot will always drive north, no matter in which direction is is pointing. In the relative mode the forward direction is mapped to the straight ahead direction of the robot. The z-rotation controls the spinning of robot.
The software and more information is available on my homepage.