Good thing you asked!
Best way to install your new footstraps with the 7mm x 32 mm PT (1 mm larger dia. than what has been used in the past) is to take one of the 7mm screws; a high quality #3 Phillips screwdriver (look for a screwdriver with the black hardened tip); and a bar of common bathtub soap.
Screw the new 7mm screw int each of the footstrap insert holes you intend to use, without the footstrap,
so that the PT screw threads "tap" the plastic material in the FS insert holes. Use plenty of the soap (rubbed on the screw) as a lubricant.Screw the bare screw in for at least 1/2 it's length.
Then assemble the footstraps, with the toothed oval washer and the K9 lock plate an install your footstraps in the normal manner, again using the soap on the threads.
If you do it this way, the screws will start in the holes nice and straight, and the soap lubricant will cut the friction so the screws go in much more easily and the threads will be far more solid and last the life of the board.
Do not use any sort of power tool!
Hope this helps,