Go here and follow instructions
http://www.thehtpc.net/htpc-tips-and-tweaks/more-channel-rows-in-the-media-center-guide/
Ignore stages 2 & 3. It didn't work for me. Had to manually grant full permissions to c:\windows\ehome\Microsoft.MediaCenter.Shell.dll
The Takeownership registry hack didn't work. I manually changed security permissions for the dll.

Enjoy.