On your iphone/touch you just need to go under Settings->Stanza->Advanced and change "Primary Online Catalog" to point to the generated xml file on your webserver.
This is a super tool! Note, though, that you don't need to change the Primary Online Catalog as of Stanza 1.5 to add your new catalog. You can just add it as a custom catalog by tapping the "+" button on the catalog screen.
Also, according to
http://www.lexcycle.com/developer, you can post a link to your catalog in the form "stanzacatalog://somehost.com/mycatalog.xml", which will cause Stanza to be launched and the catalog to be added to Stanza when it is clicked on the iPhone.