[Ninjaneer]

To add to what BK said:

mikvilja: an alternate method (but slower than using the iDrive wheel unless you want to go slow) is to use the up/down arrow keys on the steering wheel.

smellthebeans: I programmed my diamond button bring up the phone interface. There's a setting in iDrive to program your diamond and star buttons... from the main menu push your iDrive down to get to the various settings screen, then look for the appropriate option to change these options.