When I had my '08 model, I had the Bose audio unit with navigation, and I don't recall it having CD changer. Not sure which unit you have.
I'd say to look at the factory service manual here first:
Open/save the AV.pdf file. The connectors and their associated wires should be found on the following pages:
AV-80 (Base audio without navigation)
AV-253 (Bose audio without navigation)
AV-591 (Bose audio with Navigation)
I don't have any experience installing car audio components, but hopefully this leads you in the right direction. Let us know if you're able to get it working.