Finally got around to doing these and I think that there is a difference between 06-07 vs 08-10 model years or maybe the all wheel vs rear wheel options.
Holes are located behind the seats of my 08x
If you do this install be aware that the holes don't line up directly over the top of your struts. If you don't widen them the extender bends into an "S" too tightly and you wont be able to turn the adjustment knobs. Just a few millimeters more diameter was needed using a step up drill bit.
Lastly the holes are covered by something best described as a sticker of putty?? It doesn't peel, it just bunches up when you scrape it off but you can reapply it if you're careful. I wasn't so I just used the thick aluminum tape that was on the trunk wall to reseal the holes and the job was done.