Rlaw, do you use a Bluetooth communicator? The cardo scala has an fm radio in it. I know this doesn't answer your question, just trying to get you thinking in the event what you want can't be done or done cheaply.
Master Sergeant, USMC Retired
2002 HD Sportster 1200 Custom -sold
2013 XCT Boardwalk Blue picked up 1/21/2014
Vance and Hines hi output slip-ons
Lloydz hi-flow air filter
Lloydz ATS @ +4
CrossRoads HID's Hi and Low