Plan on at least a few hours....
There's a couple of write ups out there for removing the dash... The harness you'll have to see, once you get behind the dash.
Squeezing the harness past the A/C blower when removing and installing is the biggest PITA!!
Gotta disconnect the harness connectors inside the passenger fender (bend/remove the wheelwell liner), then also disconnect everything where the ABS actuator is at, to pull all that thru.
BIG STEP!!! Check the connectors for the doors and inside the fender, to make sure that they match up before you even begin. I dunno what year you're messing with, but there are MANY connector differences between pre-89 and 89+.... If it's from any 89, there can still be differences. CHECK FIRST!!! You will be pissed after doing alot of work, to find that the replacement harness doesn't work (ask me how I know).