The LED bulb is too large to fit through the eyeball opening of the trim piece, but with a little bit of effort and some machine screws, you can make the bulbs fit perfectly in the eyeball trim, and they look like they were made just for this purpose.
For each light, you will need:
(1) Halo 998 Eyeball Trim Piece
(1) 4" Recessed Can, such as H99RT
(1) LumiSelect PAR/R16 Dimmable LED Light Bulb
(2) 4x40 3/4" machine screw
(4) 4x40 nut
Step 1: Remove Lamp Socket
On the particular trim pieces I have, the lamp socket is held in place by two rivets. Using a drill bit, carefully drill out the rivets, freeing the lamp socket from the trim piece.
Be sure to remove all metal shavings from the trim piece and lamp socket.
Step 2: Assemble Light Bulb and Socket
Step 3: Fit Bulb Assembly Into Trim Piece
The lens of the LED bulb should fit nicely into the trim piece.