I used a good ol'fashioned claw hammer to pop the shifter off the tranny. You'll have to move it around until you find a good pry point and pivot point. (someone else on the forum mentioned this trick). I didn't have to crawl underneath or anything. Tremec thinks the stops should be removed, because the trans has internal stops. I would just set the stops about the width of a credit card from the handle.
Oh yeah, you gotta remove the black plastic cap from the old shifter and pop it on the new shifter. I used the open end of an large open-end wrench. Careful! That sucker will fly off and hide from you if you don't watch it.
You remove the shifter boot by curling the fingers of both hands evenly under the edge of the boot and lifting up.
With my Pro 5.0, I removed the boot from the stock shifter, and put it on the new one. I don't know if it will work with the triax. I would try just to combat the dreaded "triax whine" AKA gear noise, and keep the mechanism clean. I would consider getting a sheet of gasket material too. I've read that it can quell some of the noise too.
All in all an easy and rewarding mod. Have fun!
Don't hesitate to PM me for any questions.