Does anyone know a good site where I can get specifications for the CD changer bus? Based on the installation instructions I've seen for the factory CD changer, the bus not only carries the audio, but also has control functions and power. I'd like to tap into some of these capabilities when integrating a DVD player.

I've looked at some of the adapters on the market, and they seem quite expensive considering they don't appear to do much more than splice out the appropriate lines into RCA jacks.

Maybe I'm way off on this one.