I would park the jeep in the sun and wait till mid day or later when its warmest. I then took the heat gun and waved it over the whole windshield until it was warm to the touch. I then heated the area around the tab and then the tab, it popped right off with a thin putty knife.
Not sure how your 89 is. But on my 93, there was a unused single female connector on the fuse box on mine. I used a male spade connector and plugged in there.
'93 YJ 4.0L, AX-15, NP-231HD/SYE, 8.8in rear, OME 2.5 lift, home made front hub conversion, hydroboost. Warn M10000 winch. Currently building a stroker.
'79 Cherokee Chief, 401 MPFI fuel injection, T-18/D-20 and hydroboost. Otherwise stock.