You will have to get a Police Interface Module (
http://www.intermotive.net/Brochures/PIM_brochure.pdf ) , to bypass the Generic Function Module, so that you can make the Aux 1- 4 work as seek and volume on the PIU steering wheel ; Or replace with a Non PIU steering wheel with seek and volume and change
IPC 720-01-02 to xxx0 xxxx xxxx
and
SCCM 724-03-01 to xx01 xxxx xx
I just did the latter, this past weekend. I only have 2 DTC for the GFM , ( AUX 1 and 3 are still open ), I believe all I have to do is locate the GFM behind the glove box and disconnect and the DTC hopefully will be gone, will be trying this on the weekend.