I started doing the same thing you're attempting to do a while back (just haven't had much time lately). There are 3 different CAN BUSes in the EVO X: Diagnosis CAN-C (aka the obd2 port), CAN-B (the radio, srs, and gauge cluster are in this bus among others), and CAN-C (ECU, TCU, AWC, etc). I couldn't get more than a few error messages through the obd port.

I hooked an arduino up to CAN-C to play around and see what CAN messages I could decipher. I've only got a few messages figured out yet (although some messages contain more then one value per message). So far thought I'm able to display speed and rpm without problem by reading them off the CAN BUS. There a few others I've partially figured out including a brake pressure message and a engine cranking message.