It is under the coolant expansion tank. You can undo the 10 mm bolt that holds the tank on and move it out of the way to access the oil filter, without draining any coolant.
Just youtube "r56 oil change" it'll even bring up a video how to reset the service intervals for the computer. Unless, of course you are still under warranty and you are just doing an extra oil change to play it safe... then don't reset the computer, otherwise the dealer won't give you the freebie oil change.
It takes some looking - unbolt the coolant expansion tank and swing it out of the way, and shine a flashlight under the turbo. You'll see the signature hex head of the oil filter cap.
I might also add, the canister is made of plastic with an o-ring seal, don't over tighten it....more than a few have been broken because of overzealous wrench work - the o-ring is what makes the seal, you only want it tight enough to not come loose again.
Like x 4
