Kriss there is a routine described on pelican parts site -
http://www.pelicanparts.com/bmw/tech...Fluid_Auto.htm
also-
http://home.socal.rr.com/tyrone/SD92-114.pdf
I was looking at doing this with my wifes E36 but there was a lot of discussion on this or the 5 series forum about possible problems if you change lifetime fluid so I decided to leave it.
I did remove that big plug to check the fluid level - fluid did not pour out.
If you remove the plug just be ready to screw it back in quickly if fluid does pour out.
Bill G Melbourne Aust