There was a guy "Tierfreund" was his name, who knew everything about this kind of stuff. I haven't seen him post in a year, but he would be the best bet for help. I have lots of experience with the stereos in non-Idrive E90s, but not to much with ones equiped with Idrive. I'll help you out if I can, but can't promise too much.
"tell me what you don't like about yourself..."