Markstyle

Hey Guys, I'm going to do a major project, but don't want to discuss it much until I get the details down of what exactly I'm doing. I am looking for the wiring schematics of the plug for a 1998 Bose stereo for an E320. I need to find a way to input audio to the stock deck somehow. I do not want to go RF modulated because of quality issues. Or if there's some aftermarket add-on that will give me an input to the stock deck, I'd be willing to go that way. Basically I need a way to input audio at a high-quality frequency. I have a CD changer installed, and have the phone unit that's being removed. I was wondering if there's a way to do a device that would take the phone unit signal and basically tell the deck that the phone was turned on, and mute the regular audio while letting the audio device that I'm installing input into the stereo, using the factory sound system.
Thanks for any help you may offer,

Marcus