How to configure xml.builder to call Nokogiri?

Railsters:

I'm still on the learning curve with exotic partials. I seem to understand that a file with the extension *.xml.builder will call Builder::XmlMarkup. If so, how to configure it to call Nokogiri::Builder instead?

(CC'd to Nokogiri's mailing list, but I might get a faster turnaround here, + that list is now migrating to Google Groups...)