Thanks for the replies, they gave me inspiration . I incorrectly assumed the head of the screw would be visible out the back of the pad. When I messed with it some more, I realized the screw sinks through the pad to the plastic base, (which is why they say put WD40 on the screwdriver). That answers my length of the screw question. This next part could be wrong... Instead of trying to snap the plastic plate into the stock, I started with the plate inside the stock and pulled it back toward the end of the stock. I started a screw into one end to hold everything in place, and with a little monkeying, got the other end to take.
Looking back on it, the process is pretty easy. One diagram could have saved me a lot of trouble. It seems everything gun related assumes the gun owner is a handy/mechanical minded person. Puts me at a disadvantage.
