Again, my thread at nano-reef.com that I posted above goes into more detail about the mods. So anyone interested should check it out.
The box I used for the fuge light is just called a PVC access box. I got this one from lowes, but I've seen them at home depot and other places. They are usually grey and shaped a little different. I did some cutting so the light fixture would fit how I wanted it. I also used J.B. Weld to attached some plastic on the sides so I could use 1" velcro. I also painted it with some textured black paint so it would blend in with the back of the tank.
The light socket is a porcelain (ceramic) light socket. I found this on a spot light/utility light at lowes. It wasn't very expensive, but I kicked myself later when I found at another hardware store you can buy the porcelain light socket alone for a couple bucks. Oh well, the utility light had a cord attached so I didn't have to buy one of those.