It's possible, but obnoxious to control. You'd have to set it up so that each of the motors involved was on a different channel on the controller (one on north/south of the left stick, one on east/west of the left stick, one on north/south of the right, and, if a 4th is used, one of the east/west of the right). You'd then have to push each stick appropriately to get it to move in the desired direction. So, if you can compute vectors in your head really quickly, I guess it's possible.
