Note: I'm the EclipseLink JAXB (MOXy) lead, and a member of the JAXB 2 (JSR-222) expert group.
Your best bet is to generate an XML schema from the XML document, and then generate an object model from the XML schema using JAXB.
Example - Generating JAXB object model from XML Schema
- http://bdoughan.blogspot.com/2010/09/processing-atom-feeds-with-jaxb.html
You can leverage the Dali plugin in Eclipse to generate Java classes using JAXB:
- http://www.eclipse.org/webtools/dali/