[Zope] changing the default document

Hey guys, I wanted to change the default method from index_html to index_dtml. I did the work-around by adding the top-level "<dtml-var index_dtml>" trick, but I was wondering where within the source could I permanently change this? Also, is there an easy way that I could make Zope add an index_dtml instead of index_html each time I go to add a folder that needs a public interface? I kinda looked at the source but I'm not real good with Python (yet), so it might have slipped me by. Thanks in advance, Eron