I just hung a light for my 2x4 yesterday. This is the thread you want to check out. Cheap LED Strips : A Viable Alternative - #1151 by YoBigdaddy
In fact that link should take you to a 4x4 build another OGer did. It’s actually pretty straightforward. Just make sure you buy the right drivers. 
@Gpaw really helped me out on getting mine going after I bought the wrong one.
Here are some pictures. Good luck man!!!
