FoozGrind,
CJ3Flyr has the newer/revised version of the 70779, so more likely than not the hitch plug will be under the bumper now, located in the same area as it was originally from the factory. Where mine is located under the frame rail is a pretty dumb design on HiddenHitch's part, thus the revision.
The install is very simple. The hitch isn't very heavy, maybe 20lbs or so, but it would require some finess underneath the 4Runner to get it lined up. If you have a pair of jack stands it would help you out tremendously so you can rest the hitch on top of them and have your fiance help guide/hold it so that it doesn't slip off the jack stands.
First you'll need to remove the tie down hook on the left side, those bolts are VERY TIGHT. A rachet probably won't be enough (unless you slip a pipe into the handle to double as an extension for leverage), I used a 24" break bar to get them off. If you have access to an impact driver, it would be awesome. Then remove the wiring plug that's under the bumper, you'll most likely need to unclip the two (disconnect) plugs that are holding the wiring up along the frame rail. The last two items to be removed are the brackets that hold the bumper cover to the rear most cross member.
Now you just need to line the hitch up to the frame. I would recommend threading and getting the bolts on the passenger side frame rail in/on first, because the hitch will not go straight up due to the exhaust being in the way. Then line up the left side and tighten all six bolts that on the frame rail. I'm not sure how much it's changed, but mine had two extra bolts that used drop nuts the went into the rear most cross member. You just need to bend the tabs on those drop nuts and feed them into the access hole. Torque all eight bolts to specs, and relocate the wiring plug and you're done. The bumper cover will compress slightly, but it's very noticeable and it firms up the bumper since the two brackets have been removed. I didn't remove my spare for the install, but it would be easier.
It's a very simple install. I'm not sure where you're located, but if you're near by me, I'll help you out with it. An hour install max.
The wiring you've found in the glovebox is the brake controller pigtail harness. It allows the brake controller to tap into the 4Runner's system without the need for anything to be spliced. A popular controller that a lot of members have is made by Prodigy.