I can 100% guarantee that an iDrive controller is a simple plug-n-play item. As a retrofitter myself and using BMW's own programming software, there is no option to code the controller. You can code the headunit (CIC), you can code the screen (CID) and you can code the Combox or MULF (depending what you have) but the controller is not a codable item (it's a switch not a module).
They must be confusing the controller with the headunit, but even saying that it's not a 2 hour job, it takes 5 minutes!!