So I got the actual projector mounting done today.
I went to the hardware store to pick up some items:
- #8 x 3/4" long screws (I used 8 of them, but bought extras just in case)
- regular size #8 washers, bought ten and used eight
- large 5/32" bore "fender" washers - used them to secure the brackets to the headlight housing, to reduce the stress on the plastic of the housing
- #8 nylon-locking nuts, 8 of them were used
- right-angle brackets - I got two types since I didn't know which ones would fit properly
1) I cut down the brackets so they would fit onto the projector, and mounted them using a washer under the screw head, and another washer between the projector and the ny-loc nut.

By sitting the projector as shown on a flat surface, the brackets naturally levelled out and stayed straight. Here's another view, showing the clearance of the bi-xenon solenoid:

Note that this bracket is different from the first pic - the one shown in the first pic actually caused the projector to sit too high in the headlight housing, so the projector wouldn't fit. But with this other bracket, the projector barely had enough clearance in the headlight.
2) This part gets kinda tricky. You gotta put the projector into the headlight housing, and mark where you are going to put the screws through the housing to hold onto the brackets. I used a Sharpie to do this, and then with precision I transferred the location of these holes to the other side of the housing, where I was able to drill them out.
3) Now it's time to mount the projectors! I used a large fender washer between the head of the screw and the headlight housing (to distribute the load on that screw), and you can see the other fender washers and nylon-locking nuts.
And I did end up cutting out a little bit more of the back of the housing where the bulb holder pokes through, to make room for the bulb holder. The bulb/bulb holder can be easily removed, if I ever need to.
And a pic showing both projectors mounted up:
After that I removed the projectors, and then the masking tape. Then I reinstalled the projectors into the housings, and plugged the bulbs into ballasts to make sure that everything would work properly. Sure enough, the projectors lit up the neighborhood! But without the shrouds and because the reflectors were in perfect shape (to reflect stray light), there was some glare.
Now I have to make a decision - what to do with the reflector surfaces? I imagine with the shrouds there shouldn't be any glare with the reflector in its current chrome-painted condition. But I'm also thinking I could use some "smoke" spray paint over the chrome to get a black chrome color. Or I could paint the reflector surface gloss or flat black, or some other color (perhaps the color of the car?). What do you guys think?