I just sort of flatten them a bit with needle nose pliers on either side of the hook, start the side toward the ejector with my thumb, work it around by hand, and finish up the other end with a flat punch. Maybe 3/16 dia. or so, whatever is handy. It's no problem, and doesn't hurt if done properly. And do keep your thumb over it in case it gets loose and goes flying. If it ends up slightly rotated, just move it with a small screwdriver pushing on one side of the hook or the other. I guess the whole thing is like putting a tire on a bicycle. Start at one end and work to the other.