My e39 also have the rear mirror as same as your car. I believed my car also using IR remote originally but now i am using diamond shape remote key. I think my ex owner changed something so that i can use the RF remote now.And i found this which is showing the location of the remote receiver --> http://www.bimmerfest.com/forums/sho....php?p=4857175 Then the GM III module is use to control to open the door. I think no need to change the GM III module but this is not sure.You can take your IR remote key and go to Bavarian Auto Parts Sdn Bhd and ask them if you want to change to diamond shape remote key then what you need to change and dont forget the ask the price. The reason why i recommend you to change to diamond shape remote key is because BMW remote got memory of your car setting. It can memorize your seat, steering, air cond and comfort mode access. I think you change to the normal alarm then will lost all this functions. Post me if you get the answer.Thanks