I'm not an official part of Outlaw - I'm just a long-time Outlaw owner who spends a lot of time in the forum.

Could you cheat by learning the volume control from your receiver remote onto the volume and mute buttons of the CD device?

You may be interested to know how the Universal Remote MX series handles volume punch-through. Each device can have the volume and mute buttons mapped to a different device. Transport controls and number pad allow the same punch-through ability, although I've never used it.