To complete this project, being comfortable with a soldering iron is recommended. Even if you are not experienced in soldering but would like to learn, read up on these guides and feel free to do this mod.
How to Solder
How to Wire LEDs
This guide teaches with words as well as pictures, almost all of which have comments to help clarify what is going on during the install.
This can be a tedious install, as tolerances inside of a Xbox controller are relatively tight, the pieces are small, and expect each controller to take anywhere from 2-3 hours depending on how skilled you are. In this guide I use slow-fading RGB (Red, Green, Blue) LEDs, though any combination of colors can be used for your lighting choice.
I hope you enjoy this instructable, and are able to modify your Xbox controller to light up many nights of gaming.
*** I am not liable for any personal damage or injury that occurs from following this tutorial. You will be working with electricity (Very low voltage) and hot tools (soldering iron & hot glue gun). If you destroy your controller you will just have to spend $10 on a new one ***