I think the idea is just that you say that you used some dead man switch to store your real password. You could even have it actually overwrite some 1 MB random file and claim that it was the keyfile for the volume. In reality you wouldn't use it at all and just memorize the password like normal, no one would be able to prove if that really was a keyfile or just a decoy and you couldn't be in contempt of court if you can plausibly claim that you don't have the information to open the volume anymore.
