I think your best bet would be to use XPath to pull out the data. For example, you could use the xpath function in an expression shape to extract a value:
strData = xpath(soapMsg, “string(//*[local-name()=”Data”])”);
You can use the Dan Sharp XML Viewer to build and test your XPath statements: http://www.bizbert.com/bizbert/2007/11/25/DanSharp+XmlViewer.aspx. Just run the tool and open a file, then drill down in the XML tree to the data you wan, and it builds the XPath for you.