So you don't mention what type of transmission the car has. If it is a manual and depending on the mileage I'd replace the clutch and related components (slave cylinder, etc.).
I've not yet pulled the tranny on my car, but I've done a few other BMWs in the past. There's really no magic to it. I've done all the below except pulling the trans.
remove the exhaust
remove the under panels
remove the drive shaft
Remove the transmission
Replace the seal
The oil pan seems a PIA if you don't drop the front subframe. If you are using a lift, I'd vote for dropping the subframe to get the proper clearance to work.
If you are digging this far into the car, I'd suggest buying the Bentley service manual; it's a good reference for what you are doing and keeping the car in the future. The TIS is a nice resource, but it is written for factory trained techs so there's not a lot of detail.
Attached is the Guibo/driveshaft replacement TIS procedure.