The rubber gasket comes as a six foot piece. You stretch it tight around the glass and then cut it to size. Remove the rubber and super glue the ends. Let it cure for 24 hours or more and put back on the glass.
You can position the joint any where you desire.
The hard part is getting the washer and nut on the 18 screws behind the frame. I finally bent a 3/8" open end wrench to almost ninety degrees and then super glued a thin magnet to back of the open end. That held the nut and washer on the back side of the frame while I started the screw.