In this situation I've alwas iterated over the list to create a list of hidden fields. Like this:
To do this in a single tag I would think would require you to make a getter that could turn all of the data in your list into a string and a setter that could convert all of the data from a string back into your list. If there is any easier cleaner way to do this I'm interested to know it as well.
subject: how to define a list as a hidden variable