Hi Mark,
Yes that's possible to accomplish - you should put the expression that generates the XML formatted label in the Values Grouping\General\Label field - for example:
=Fields!ContinentName.Value + "
hello labels"
and set the data label format to:
"<label>"
That way your expression will be evaluated for each data point and the result will be displayed in the label.
Hope this helps - let us know if meet any problems or have any questions.
Best Regards,
Nevron Support Team