Stick around a while. We have a couple of guys that live in Florida that might be able to help you more directly. In the mean time, I'm not from Florida and I never heard of a hurricane shelter. I've hear of Tornado Shelters though.
Here's a bunch of FEMA links that might be able to help you. FEMA Downloads and Tornado SHelter Plans. If you want more of this 'stuff', I can get it for you. Just post back. (I'm kinda assuming you haven't built anything yet.)