First of all, flipping a toggle to go from 2wd to 4wd is
You said you had a "part-time case". In 95' ZJ's this could mean either a 231 (2wd, 4 hi, 4lo) or a 242 (2wd, 4ft, 4 hi, 4lo). I assume you DO NOT have the 249 since it does not have a part-time mode.
I know nothing about Explorers and can only assume that "4 auto" means there is some sort of differential inside the transfer case that does not split torque 50-50 front to rear. I further assume that by "4 hi" you mean the torque split is 50-50 front to rear. If so then it makes alot of sense why this brown wire mod is popular with the Explorer guys.
Now for the good news. No matter if you have the 231 or 242 t-case, the 4 hi mode locks front and rear together. And you already have a toggle to go from 2wd to 4 hi; its called the t-case lever.