I just did mine with the help of a friend. I should have documented
it. You essentially have to unbolt everything connected to the oil
filter housing. Then there is 6 bolts holding it to the motor. My
gasket was fried.....bits were stuck to motor. Chip it out of its
grooves and cleaned up where it mates to motor. I also switched
out the vanos oil line, $110, it connects oil filter housing to top of
motor. put it on with housing off car. was recommended to be
done by BMW master tech.
Not too bad a job......tedious.....maybe 3/4 hours poking along. IF
you had done one, maybe 1.5 hours........

BTW stopped leak completely. Prior to this repair I did the oil separator,
now thats a real pain in the ass. I had to break it up getting it out
of car. Then its contortionist time to put it back in. the bottom hose
that goes to oil dip stick had completely rotten off! I was dumping
oil, a qt a week.........