I also have the ABS system that was installed in the 89-91 rigs. After waiting for 23 days in 2003 while Milam Jeep in Puyallup, WA tried to find parts that they later discovered they already had on the shelf, I decided to do away with the ABS entirely. Doing away with Milam Jeep is another of my life projects.
I first started by removing the ABS BATT fuse (I think it's a 2 amp fuse) and the brakes worked normally and the ABS was off.
At some point you will likely want to pull the bulb on the ABS light on the left side idiot panel. Pop the dash bezel off, unscrew the cover and gently pull out the offending bulb.
When I did an axle swap to go to 4.10 gears, I took the opportunity to remove the ABS computer, all the tone wheels, sensors and wiring from the rig.
After having done that, the brakes work well, no scary surprises and if history repeats itself, I shouldn't have to replace these parts again until I have 360,000 miles on the rig. The accumualator and actuator/master cylinder have both lasted about 120,000 miles and I'm on the 3rd one since new.
If you have any questions, feel free to PM me.
John