I think you might as well just ghet the adapter ( CD-RB20). It's lot of work to do the things you wanna do.
I also got a IP BUS related question. I recently used the IP BUS pinouts and soldered on to the circuit so i can get the AUX IN.
But for some reason I get the music from the mp3 player and also this strange noise. I have the CD-RB20 and as soon as i plug in the IP BUS cable on the back of my HU, the noise stops. Could it be bad soldering? bad grounding? I dont understand what's going on.... please help! If I can get the sound to come out clean I will be selling my CD-RB20.