Aure you sure your car is regenerating from 70c ?
I read somewhere it needed at least 75c coolant temp and a certain exhaust temp.
Hidden menus are here : http://e90.wetpaint.com/page/BC+hidden+menus
Essentially you just need to press the trip stalk in for 10 seconds and go to menu 19 UNLOCK. I think you have to add up the numbers on the display to find your passcode, after unlock press until you hit your passcode number then go to menu 7 once unlocked.
Hidden menu should clarify it.