I would try using appfuse:gen-model:
http://static.appfuse.org/plugins/appfuse-maven-plugin/gen-model-mojo.html
Note, that AppFuse isn't great at creating relationships between classes, so you might have to do some work after it generates the code. You also might try searching the user mailing list archives:
http://appfuse.547863.n4.nabble.com/AppFuse-User-f547864.html