Wasn't sure where to put this as it applies to both the Z3 and Z4 but came across this write up on stripping an M54 and gives a very detailed explanation of where various parts are and how to get at them. useful as a reference at least.
http://forum.e46fanatics.com/showthread.php?t=899347
http://forum.e46fanatics.com/showthread.php?t=899347
. I hope I never have to do an engine strip down but if I did...