You can look up into the shifter mechanism from below to start with. If that shows OK, you can pull the boot on top but as I recall, there is not much to see there. Almost everything is accessible from below.
There is also an adjustment you can do if there is no clearance between the shift lever and the cam plate in the front in 2wd-hi and in the rear in 4wd-low. I have added the adjustment instructions below. Ignore the statement about raising the boot to expose the top surface of the cam plate. You will have to remove a lot more than the boot to expose the top of the cam plate. As I said before, everything should be accessible from below.
If you do lift the boot, don't use the fake Allen head screws. They are for show. You can just lift the boot out of the chrome plastic frame.
2002 FX4 Bright Red Supercab 4.0 SOHC, manual 5-spd & Tcase, 33" BFG MTs, K&N air filter, Modified air box inlet, Gibson SS cat. back exhaust, Bama flash, Hidden Hitch round receiver, Rear helper air springs, Electric trailer brake controller, Line-X bed liner, WAAG bar with KC lights and Wildernest shell.