[Zope] dynamically generate dtml-tree urlparam attribute?

hi, i was wondering if anyone has either hacked the dtml-tree code or written a python script to create a <dtml-tree> tag with a dynamically generated urlparam attribute? i currently have a <dtml-if/elif/else> that selects from 7 prewritten <dtml-tree> tags, but i was hoping there was a better/slightly more elegant way of doing this. -jason yee