I just went through this tonight on my 2008 535xi. I somehow managed to get the old mechatronic sleeve out, albeit with a bit of force. I saw on another post that two guys had done it, so I thought what the hell. As for the new sleeve, I didn't want to damage it, so I ended up biting the bullet and dropping the rear transfer case mount in order to install easier.

To remove the rear transfer case mount:

1. Remove 4 nuts (10 mm) where exhaust pipes meet downpipes.
2. Remove heat shield bolts (various 8 mm and 10 mm bolt/nuts) - just let it rest on top of the exhaust pipes - you're just trying to make room to remove the transfer case bolts
3. remove 6 transfer case/tranny mount bolts (13 mm I believe)

At this point, the bracket for the transfer case/rear of transmission is low enough that you can reach above it to slide the new sleeve into it's position.

Hope this helps someone out there dealing with the same situation on these unique AWD 5 series cars. I just did this job a few weeks ago on a 335i and it was a breeze, because it was RWD. The AWD components add complexity and create tight packaging.