My P2 Si came with a factory optional Sony head unit that had a steering column controller, which plugged into the back of it using a 2.5mm audio jack connection. I've put an Alpine 9843r unit in there and was wondering if it is possible to use this controller with my alpine unit, or whether it'll work with the sony unit only. If not, is it possible to buy universal steering column controllers? Or do they have to be factory fitted to the car.