Assuming no change in the transmission between the E70 LCI (production after 90/2010) and the F15, the gearbox release mechanism is a large set screw/bolt on the (left I think) side of the box. I believe the bolt is part of the selector servo mechanism?
E70/71 have a protective shield which must be removed first. I've never seen a pic of the underside of the F15 but it's very likely to be the same.
The previous gen cars where the release key worked had a key slot (under a removable plastic cover below the left front cup holder) into which the tool went and was pushed down and turned 90° to disengage 'P'. That has now gone. My X6 just has a view of the top of the gearbox when I remove the cover. All the tool does in mine is disengage the handbrake.
If you are without electrical power then as you also have to release the electric handbrake manually the car will roll without stopping!
From what I have read, recovery means a full lift rather than a winch on job.
If you have power then the procedure in this link to a
thread on the forum may help.
I have also seen references to this procedure - and it is only for pushing it off the road. 'P' re-engages automatically after 15 mins - disastrous if being towed (not that you should be being towed in an AWD auto.
With ignition on (but no motor start):
Hold left button on the gear stick while doing (LHD US cars -so may be right button for us?)
- put gear stick one step forwards and hold 2 seconds,
- then one step back again
- then one step forwards again
Then the car is in neutral for 15 minutes after which 'P' re-engages
Whoever designed this process really wasn't thinking it through....or the bean counters got in the way!