Unscrew the knob and set aside. There will be a spring in the hole underneath. Pull the spring out and set aside. The reverse lever is held in place by a remnant of the OEM lock out cable. It is now just a sharpened 2" pin with a plug brazed onto the end. Pull the reverse lever upward sharply .. maybe several times. The plug/pin will dislodge and come to the top of the barrel of the shifter. Pluck it out with your fingers .. now the horizontal lever is free and you can slide it out. Install your boot. Now reverse the process to reassemble. Getting the pin to go back in the tiny hole in the reverse lock out lever is a b!tch. Easier to just unbolt from the tranny and slide the boot up over the bottom. But I learned this on the toploader, which has a big plate on the bottom.
Sorry, can't do pics right now .. car is in the shop
Sam