Rather than XSD (xml schema definitions XML Schema (W3C) - Wikipedia, the free encyclopedia), I think you mean an XSLT (XSLT - Wikipedia, the free encyclopedia) to transform the FMP xml export into the schema that you need to send somewhere else. You should have access to the XSD(s), if any.
the XSLT can be written to "map" the COL/DATA elements from FMP into the <elementName>. You might be able to see an example of XML that needs to be created.
If you don't want to create an XSLT, you may also be able to calculate the result XML (it's text, afterall!) such as this forumla:
= "<elementName>" & tableName::fieldName & "</elementName>"
Again you need the XSD (or DTD or other description of what's needed) to know what the result should be.