Good idea on the tape to help hold them in place. I also plan to go out and pick up some ribber washers like RangerMuse did.
I got them fitted in today, but still have the finish work to do, as well as the wiring. Anyway, here's some pics of how I mounted them.
First, I removed the grill, surround, and the black cowl:
which left me with this:
I then measured, and marked it off with tape as a guide:
The mounting location has two levels (you can see it once you get the front pieces off). I used a hole saw to make the larger hole in the top level, then the recommended 10mm bit to make the actual mounting holes.
Then I just bolted them in to see how it looked:
Like I said, I still need to clean up the install, wire them up, and then aim them. Painting the grill comes next.