Not as much progress as I'd hoped. The RPi and empeg apps are fine -- I added album art display, configurable track data, etc. and it would be usable as-is if I could get the freaking CAN stuff to work. I can read CAN data on the OBD-II connector, but for some reason I can't get anything from the CAN-B (convenience) bus that connects to the radio. It's probably something stupid where I messed up a connection somewhere, but I've tried a bunch of different stuff, and since nothing's documented, it's hard to tell the "baud rate isn't what I think it is" problem from the "wires aren't connected" problem, since the CAN chip initializes successfully either way. I spent about an hour on it tonight and got frustrated, but am hoping to take a look again tomorrow to triple-check connectivity, maybe try something different with the Arduino code, etc.

If I can't figure it out, I'm probably just going to punt and order an IR extender so I can have something usable in the car. The major drawback to that (other than the fact that I'll need to reach for the remote all the time) is going to be that it takes six or seven button presses to switch back and forth from the Lockpick's A/V input to the factory stereo (something I was hoping to automate with the CAN stuff.)