From a novice standpoint I'm not touching the tranny until I grow a pair. But the manual is worth buying, as it has all the specs and process down.
Thought I'd post something that gives perspective on how the people behind the scenes do a change (and that they do a change, for $400 bills for that matter).
The way they do it, I'm considering sending my car on vacation and hoping it comes back with t shirts from the airport.
BMW E38 Transmission service by ZF Germany - YouTube