I know that you can get the buttons to work as the head unit is steering wheel control ready. I have seen a thread where some one made buttons to control vol, mode, and couple other things and placed it in the center console where the seat heater would go. He had to run wires and do up some circuitry as it uses a series/parallel resister system to tell the head unit what button was pushed.
With that, I dont think it would be that hard. I'm sure the steering wheel buttons have the resistor circuitry already. If there is no wire harness just make one or look up and see how one would look for a TC or almost any Toyota with steering wheel controls.
Read through this. Its alot to take in but with 17' steering wheel ready there would be nothing to fabricate. You may have to do up a wire harness but just read and see what happens.