it's fucking gnarly but I quit by starting dipping and then quit dipping.
i know it sounds like trading one vice for another and it is, but my thinking was that because dipping is so socially unacceptable it would be easier to quit.
think about it this way, if you were in a bar full of women would you dip? most likely wait till later.
if you are waiting for a bus, couldn't you most likely bum a smoke? sure. could you bum a dip? not likely...
anyway, it worked out for me, but might not work out so well for everyone.
otherwise, get a shit load of gum and trade out that way.