Ask a lawyer, that's what they're for.
With legal advice that costs you nothing, you get what you pay for.
-(a different) Craig
-- There are several websites that deal with knife laws, and there are many magazine articles, too. Almost all of 'em only quote the basics of the law, and they're all pretty vague (can you define in legal terms what a "dirk" is?). For actual advice on legality, again, ask a lawyer.
Easiest thing to do in most cases (IMHO), don't carry an auto, don't carry anything over, say, 2 to 2-1/2 inches, and obviously don't wave it around, but that's pretty standard advice, isn't it.