I have never bought into this. Why is it any better to be frozen than boiled? Both are horrible things if you are able to feel them.Sure they have feelings... probably not emotional ones however.
USe the Alton Brown hint: put them in your freezer for 10 minutes or so. Puts them
"to sleep" before you dispatch them.
Here is an illustrated guide to dispatching a lobster with a knife.
If you are going to toss them kicking and screaming into a pot of boiling water DO have the lid to the pot handy and pop it on after you put the lobsters in until they quit kicking or you may have to chase your dinner down as it scampers across the counter or floor!
I don't believe in the knife to cruel to me --