The Rockford in my 07' Off-Road was what I loved most about my truck...I'm also a sound snob LoL
I don't know much, except for this...
My 07' had a factory aux jack located just above where the aux outlets are on the right side of the center console...next to the glove box.
My 05' Off-road does NOT have an aux jack...so, they must have started adding them in 07'. If you can find someone who has an 07' maybe they can trace it back and tell you how it works from the factory...
P.S. I bought my 13' Pro-4X for 2 reasons...locking diffs and Rockford Fosgate