Here is a link to Stanley's shield I use, I just have the shield and a standard mega. He has a cable that will interface with our cars as we only use K-line (04-07) and CAN bus (08-11), but it is a bit more pricey than the generic ELM cables. He uses a 32-bit PIC controller to handle the protocols.

Freematics – OBD-II Telematics Advanced Kit (Arduino MEGA)


For flashing the ECU I have yet to source a cable/interface that has been tested and I am working on that at the moment. Right now your only option on 06-08 ECU's is to pull the flash chip off and read it in a Willem type reader with the amd chip adapter.