Here is a neat trick to remove the Serpantine belt using a shop rag.
It works on a V6 Duratec. I am not sure what other configurations or engines it works on. Does anyone else know?

 

I have actually seen someone remove the belt with their bare hands. It must have been a very weak tensioner. I am not sure how they put it back on.

Here is the prefered way if you have a 3/8 square drive in your tensioner.