Fit your paddleshift steering wheel and swap the connector over under the dash on the 450 and Roadster.
There is no connector to swap for the 451. If it doesn't work after coding, check the wiring.
Plug the MB Star multiplexer box into the OBD port of the car, turn on the laptop and boot up DAS.
Press unlock on the key, place it into the ignition and turn it to position 1 to power the car up.
When you get to the main screen, press F2.
Scroll down to "smart" and press F3.