After pulling out the capet cover, you'll need to also remove the styrofoam pieces that hold the basic car tools on both sides of the spare wheel. They're each held in place by a single plastic clip (circled in yellow). I removed them by pulling the entire styrofoam piece straight upwards. Might have been my luck, but nothing broke, so I continued onwards. Simply bolt in the strut bar by lifting up the flaps that cover the bolts (circled in red).
The tool holders won't fit back into place without a little cutting. You can probably get away with cutting a smaller portion out from the bottom, but I cut it so that I could take the bar off and back on without having to take the styrofoam pieces out again. Remember to pop the clips back in so they don't fly around when you're driving around.
The carpet cover also needs a trim to get it back in place. The directions given calls for cutting out pretty big chunks out, but I found you only had to cut along the yellow lines. It does require a bit of shuffling around to get it back in, but looks better than how the directions would have you cut it imo.
Hope this will help others. I'm guessing this'll be the same way to install any rear strut that comes out.
I added one of these to my old Type-R for the sole reason of having a good place to bolt my BassTube to. By the way, a Basstube is the lightest way (I'd guess mine weighs maybe 5 pounds) that I've found of adding a sub without bolting in a ton of weight.