Sorry, I'd have to try to see if it was possible. I know you can not turn on the 'ML63' AMG menu on my ML500. But then the dash in the W221 may be the same for all cars since its completely "soft" (i.e its just a big LCD display) ..
Turn ignition key to position 1 or 2.
2. Turn on Command.
3. Turn to Radio.
4. Press 5 (continue holding and wait 1 second).
5. Press 3 (continue to hold along with 5 key and wait 1 second).
6. Press 7 (continue to hold along with 5 and 3 keys and wait about 3 seconds).
7. A menu should appear. Scroll down and select "AMG211_ECE" option.
Turn ignition key to position 1 or 2.
2. Turn on Command.
3. Turn to Radio.
4. Press 5 (continue holding and wait 1 second).
5. Press 3 (continue to hold along with 5 key and wait 1 second).
6. Press 7 (continue to hold along with 5 and 3 keys and wait about 3 seconds).
7. A menu should appear. Scroll down and select "AMG211_ECE" option.