Slightly OT: Java, XML, JTree question

I know this is slightly OT, but...

I have a Java program that displays the XML document in a Java JTree.  I want to be able to edit the underlying XML by clicking on the JTree component, however, I am confused by how to reference the JTree component in the DOM...

Underlying it all is:

an XML document
Using DOM to parse document and create the JTree
Output JTree

If someone clicks on the JTree, how do I reference the XML component in the DOM (say I want to add an attribute to an element)...

If this is the wrong place to ask, then sorry, but I'm sure there are people out there who can help!

Paul