So you have a manual mirror at the moment and you want an auto dipping mirror??
Yes that's a possible retrofit. I'm cu6in the process of undertaking this mid myself, but other mods have got in the way You do need to do some extra wiring and coding for it to work though.
Once I have it done the mod will be up on my YouTube channel.
Thats good news to hear from you.
Perhaps you already know which mirror type to buy, i think a mirror from the e90 fits also?
Your Cruise Control How-to was great, so looking forward to this mod.