Third party is doomed to failure. The Democrat/socialists/communists are united and will vote in a block--about 43-49% of the vote based on the last few elections. Just read a portion of Whittaker Chambers book "Witness" about the devotion of most communists. They stick together.
However, if presented with a situation where the GOP nominee has no chance, as we would be if Huckabee somehow got the nomination, then I would consider using this as the opportunity to send the message. There would be no damage from my vote, and maybe it would help reform the party for a better run the next time.
I think Huckabee's chances of getting the nomination are very slim, though, so it is merely a hypothetical. I am a Hunter 1st Fred 2nd no one else third voter. If Hunter can't do it, then I sure hope Fred pulls it out in South Carolina. I would accept and vote for Romney or Giuliani in the general election, but not gladly. They have a shot at winning, so I would not support a third party candidate against them, as it would only ensure the election of Hillary or the Obamanation.