Yes it works. No drilling required, unless you want to use all 4 holes. I am just using 2 and it is secure. Use a washer when you screw it in so you can screw it in a bit harder.
By the way, the screws are M6 16mm and they didn't come with the wheel (but maybe you have them from the G27?)
Pic of Fanatec PWC with WSP
^^^Is that WSP for the G27 or GT?