Somebody must have put these things on.
Take your time, start at front edge, top hook goes over first, pull down with fingers & push in with thumbs, bottom snaps on. The trick is to get them started first along the top about a foot and a half (not fully popped on) then go back and fully pop on first 6 inches, then start 6 more, seat 6 more...to the end. Fully seat them with the palm of your hand or a rubber roller (like the one they sell to install Dynamat). Put on a set of heavy leather gloves or something with padded palms if using hands. Their really not that bad, just take your time.
Also, since you mentioned the vinyl top...it should end DOWN IN the gutter...there is a space to tuck it into. There is also a special retainer that is supposed to go over it in the gutter. If the vinyl is wrapped up or over the piece you put the molding on you will never get them on.
See this thread:http://www.camaros.org/forum/index.php?topic=3133.0