Actually, if you have the CORRECT version of the Recaro Pole Position, then the buckle/clicking mechanism DOES fit into the hole of the seat.
Just this weekend I installed my Recaro PP's into my car with the ScienceofSpeed Sliding Seat Rails. Had no trouble getting the seat belt holder in the opening.
However, it is seated VERY deep into the seat, which makes it difficult to click the seat belt in. It certainly takes some time getting used to.
The correct type of the Recaro Pole Position you should be using is the ABE version. The FIA version is the track oriented version and is more suitable for use with a 4-point harness instead of the usual 3-point system.
I took a whole bunch of pictures during the install, but haven't had the time yet to take them from the camera.
Will see if I have some time left tonight and put them in this thread.
Update 0706:
Here is a short completely unedited movie clip about how to mount the seat belt recepticle to the Recaro Pole Position seat.
http://www.youtube.com/watch?v=T2SRRiR1P0g
Enjoy..