Here's how I install them:
I used a long flat piece of brass metal I got from Ace Hardware, bent it a little, and stuck a piece of two-sided tape at the end to hold the Glass Eye.
Before you glue the eye in place, make sure it sits flush enough for it to be glued in place. If you want the Glass Eye to sit completely flush with the eyelids, you may have to grind away a little metal with a Dremel Tool. Just apply a lot of tape around the eyelids, so you don't damage the gold-plating while grinding on the inside of the eyelid.
I then guided the Glass Eye to the eye socket and then held it there while I added some Superglue, while holding it there for another 30 seconds. Release the metal rod from the eye and then turn the Idol over while the glue dries for another 30 minutes. Then repeat the process for the second glass eye.
I then fill it with spray foam, which secures the eyes in place even more and fills the empty space. I then cut out a little bit of the foam around the bottom hole and filled it with plaster, let it dry for 24 hours and then sanded flat. I then sprayed it with Spray Adhesive, applied Gold Leaf, and let that dry for another 24 hours. I then sprayed it with Clear Polyurethane Spray and let it dry for a couple of days to cure. You can even put it out in the sunlight to cure even faster. The Gold Leaf may start to form bubbles while it's drying, which you will just keep popping them as it dries and press them flat. If you expose the glue underneath the Gold Leaf while popping the bubbles, just add a little more Gold Leaf.
It's a little tricky getting the Glass Eyes glued into place. So, take your time and be patient!
Best of luck!