I fitted socket a few years ago, if you search the forum, there are some excellent posts, including pictures. Also if you try google. All I did was get the ready made lead from Bmw, which extends the power from the power socket under the seat - just plugs in and the other end is long enough to reach the beak.
Just like this kit from Motorworks - Power point kit ( R1200GS up to 08/2006 ) | ELA85121 : http://www.motorworks.co.uk/vlive/Shop/Parts.php?T=5&NU=15&M=35&Ct=IA&SbCt=BA_15_35_IA_80
With the drilling, I started off with a small pilot then a little bigger before finishing off with a file. I protected the plastic with masking tape.
First look underneath the beak and you will see a steel subframe. Cover the top with masking tape to prevent the drill from slipping. Drill a very very small pilot hole and then look underneath to see where the hole came out. If the hole is not centred in the middle of the
Yes you need to leave the beak on so it will match up with the hole in the subframe. You could remove it and try to line up but you are making life hard for yourself. I would personally would use a small drill bit rather than the step drill as this is a safer method. Remember if you add too much salt you can't remove it and you can't make a hole smaller (well you can but it would look crap).