The Steering wheel buttons on the E46 are not resistive driven. so it's unlikely adjusting the resitor wheel will do anything.
TBH you are probably better off using an iBus interface (search Resler) and use one of the many programs that convert that to keystrokes.
If you are using one of the FrontEnds on here, most will already have a plugin available for iBus.
Also with an iBus interface you can get much more info out of the car and also control some other things as well ;-)