I've always like this article on the subject
http://www.sailnet.com/forums/gear-m...ing-shine.html the increasing levels of work for a restorable hull are waxing, polishing and waxing, compunding and waxing, whichever is needed.
However if the boat is not white, you may remove the chalk but even with a whole lot of work you are not likely to bring the color back for more than a month or so, then the boat will again look chalky. Colored boats need to be painted to look good, period.