Better yet, S-Video without the chroma line.
(Yes, I know that would be basically Composite without chroma in the signal, but a dedicated S-Video jack would ensure you are getting NO chroma in the signal).
I didn't do a composite mod, but I did do the S-Video trick, and the results were pure awesome on my 70's-80's black and white set.
http://www.youtube.com/watch?v=PY60CpSXlog