Start with a practice piece of track.

1. Measure one half inch back from a divider on the underside of the track.

Hole placement should be in between the outside electric rail and the slot.

2. Place the tip of the knife where the holes are to be drilled and scratch a line in the plastic.

3. Place the tip of the drill bit at the end of the line that you started the scratch with the knife. Pressing down, turn the bit clock wise to carve out a small seat for the bit. This is to prevent the bit from wandering when you go to drill the holes.

4. Put the bit in the chuck of the drill. Place a piece of wood under the track. DO NOT APPLY DOWN FORCE! Allow the bit to cut all the way though making I nice clean hole on the top surface. You now have a 2.5mm hole.

5. The eyes are 3mm in diameter. Place the drill bit in the hole, apply power to the drill. Apply pressure in a circular clockwise motion to gradually increase the size of the hole. The plastic is soft, it doesn't take much. 

6. From the top side of the track continue boring out the hole until the photo eyes just barely fit in. If you have a snug enough fit you may opted not to use glue

7. Now try the fit from the underside. If you find that the lip of the eye prevents the eye from seating straight, you will need to file it down. Notice that one side has been manufactured with out the lip. This is to make the cathode lead.

8. Once fitted apply a tiny amount of super glue to the sides of the eye using a straight pin to apply. Press the bottom of the eye into the track using a small standard screwdriver. The eyes should be flush with the top surface of the track.

9. Approximately two inches back from the eyes apply a drop of super glue in the trough and dress the wires down tight. This will act as a stress relief for the eyes. All set!