Dana, I found something interesting in the documentation.

The solution is along the lines of what the other poster suggested.

I think you can redirect the DTD lookup to a local file by using the resolve_entity method. It says that you "can use this method to redirect external system identifiers to secure and/or local URIs, to look up public identifiers in a catalogue, or to read an entity from a database or other input source (including, for example, a dialog box)."

From CPAN