Sheldon's method isn't going to hurt anything on a structurally sound steel frame, and it will insure good alignment when you're done. The tools needed are a 2 x 4, a string, and a ruler. Sheldon didn't write instructive articles on these subjects without knowing what the result would almost certainly be. As Grand Bois said, follow the instructions carefully. I also agree with Grand Bois on this point: don't try to outsmart Sheldon. Particularly when dealing with an old steel frame.