Hello Forrest,
I wrote a first blog some day before: http://dotnetnuke.com/Community/Blogs/tabid/825/EntryID/1038/Default.aspx
I know that it is difficult to write your own XSL without any documentation. As the author of this enhancement I am feeling a bit guilty that I included a link to the xsl but not to the current XML.
Nevertheless you can catch the XML in a few steps. Define your UDT as you like and add some sample data.
Open Pretty Print XML using XSLT (http://www.printk.net/~bds/indent.html), copy the displayed xsl stylesheet and save it as prettyPrint.xsl. Open ManageUDT, go to the display settings (for current page), select User Defined XSL StyleSheet and upload the stylesheet. Select it and save.
Now you will you see the whole inner text as output. Open now the module in print preview, change to html code view. You will find the xml document starting at line 25. The opening/closing tag is UserDefinedTable. Copy it to a new file and save it as data.xml. Now you have a working copy of your UDT Data to create a XSL stylesheet with your favorite tools offline.
The direct xml output for everybody with manageUDT permissions will hopefully get into the next UDT release, it is on our roadmap.
Thank you,