Modify seat ribs. The two center seat ribs need to be modified by cutting a round hole in the top of the opening. Then the nutplate is cut out of the top so that it will be removable in the future. Unfourtunatly the instructions don't explain it like that. The drawing shows the lighting hole modification and then removing the nutplate area. It was only later that I realized that the nut plate stays. Since I didn't cut it in the right place I had to make a small plate to rivet it all back together. No big deal, just another case of not understanding the drawings and unsure of how all of this fits together in the larger picture.
