Or "How to be a manly man."
First: check you have all the tools. Especially all the fun ones.

After your car is up on the ramps, and you've partly removed the muffler to get to a sheet of metal, you get to drill a hole in it! Yay!

After that you need to remove the rear bumber completely. Which means "Oh crap... I don't have anything to get in to there! What the f&^#$(*^!". Thankfully by then, Dr Scruff had come to help, and point and laugh, so we drove off down to the local purveyor of hardware and found a tube spanner which had better do the trick or we were toast. If it didn't work, I'd have a superfluous hole in my car and have bits everywhere to no avail.
Luckily it did work, giving an interesting new look to the car.

Once you remove those metal caps on both sides, you can see down the chasis. Take a look down my chasis *nudge* *nudge* *wink* *wink* say no more.

The wires you can see poking through those holes are what is provided to orient some metal blocks that the towbar gets bolted to.

Then there was the wiring. This photo was taken in case we didn't quite get it right and had to go back. The plug, and another one, needed to be pulled apart and all the wires removed and put in to different plugs. Why didn't they just provide the correct sockets the first time?

Thankfully once we wired it all up (and checked it with a multimeter) it all popped together quite quickly, and we barely needed Dr Scruff's big lamp. Of course, I owed him a beer.

The next morning I was very nervous as my car refused to start. Thankfully that turned out to be a one-off, and it's been happy ever since! And I feel like a real man:
"What did you do on the weekend?"
"Fitted a towbar to my car."
"Have you used it yet?"
"No."
"What are you going to tow?"
"That's not important right now. I have one and I did it myself. Well, with some help."
I do have to thank Dr Scruff. Without his help I don't think it would have happened.
p.s. according to the provided documentation the process should take 1hr 45mins total. Including removing the interior and putting it back in twice. We took around 6 hours, excluding the beer.