on the second page of the thread jimmy says you just have to cut the bottom half of the frame down 1" to get it to lay rocker. I have seen this done on other truck sites. Check this site out so see a over view on how to get a square body down in the rockers.
http://www.loweredd.com/Frame_Z.html
Maybe some one that knows what they are doing could check out this site two and let me know how good it is, or whats the best way to go about it. I am going to try it on my truck this winter.