Access Dojo widget on grails form submittal

I have a dijit.Tree which has a store and treeModel assoc开发者_JAVA百科iated with it obviously. I have customized the tree to be a "Checkbox tree" so that the values in the tree can be checked. How do I pass this treeModel back to the grails controller?

When I was using a native dijit.HorizontalSlider placed within my g:form, the value got put in params automatically. I can't figure out how to send more complex values as poart of the form submittal