This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I'll give you the answer I give my clients when they ask if something outrageous is impossible.
"Sure it's possible, but it's going to cost you!"
In order to do this outrageous and completely unnecessary thing, you'd have to extend the Struts ActionServlet to read a database instead of an XML file. Since Struts is open source, you could obtain the source and figure out what needs to be modified in order to do it.