I just performed the mod myself on the 2009 335i X-Drive Coupe. Mine featured an iDrive. The hardest part was removing the center console area. All you need is a Torx 10 Screwdriver and alot of persistence.
Took me 30 minutes to remove the console, then 10 minutes to replace the ashtray with the sunglasses holder and put the console back in place.
Make sure to remove the connectors from the iDrive and the ashtray area after the console has been removed from the housing, but before completly removing the console.
Is it me, or is it the Bimmer?