What I hear you saying is you are wanting to get the value for this field from an XML data set.
I've played around with this a bit and it doesn't seem like the XML data set wants to play nice with the other spry widget. Basically they won't interact together. If you have a link or page that says differently please let me know so I can see the method but as far as I've read and tried it hasn't worked.
If I were you I'd use some sort of server side scripting to plop the value in. An SSI or whatever you please.
Abraham
