I have a new X920BT in my 2006 Toyota Sienna. The Sienna has five steering wheel controls: volume up / down, track up / down, and mode. I think my PAC SWI-PS can control more than five functions. Is it possible to add some sort of aftermarket button(s) to my steering wheel to add some additional functionality? For example, my steering wheel "mode" button is currently programmed to "mute" with the SWI-PS (my choice), but I would like to add "home" and "mode' functionality to my steering wheel as well.

well you could add new buttons to the wheel, but you would have to have a different resistor for each one and they would have to be different resistances than the buttons that are already there, then you would have to tap them into the wire for the stock buttons so that you dont have to deal with the clock spring, yes it is possible but it is very difficult and you will have to be careful