The seat back release button pops out. Its just clipped in. Behind that are the two screws you cant find :laugh:
The whole thing pops out. Here's a pic of one on Ebay. You can see the clips on the sides in the pic. Get something underneath it and be careful to not scratch the plastic http://cgi.ebay.com/ebaymotors/1969-1970-1971-1972-Chevelle-Seat-Back-Release-Button_W0QQcmdZViewItemQQcategoryZ42612QQihZ016QQitemZ260319124501QQrdZ1QQsspagenameZWDVW
After you get to those screws the plastic has to be lifted up towards the headrest to release the tabs from the grooves in the frame. There are also screws on the very bottom that you have to fold the seat over to see.
It really helps if you can get an extra set of hands to help...have your helper push down on the bucket seat back plastic while you slip whatever tool you use in on both sides of the chrome button. This also helps you avoid scraping up the chrome along the edge of the release button.
a couple of dinner or butter knives work fine. slide the knives between the button & it mount/frame to release the clips.