You could export a tablebox or a table-chart to xml - maybe with a triggered macro like this:
set tb = ActiveDocument.Sheets("Main").CreateTableBox
If this don't work you will have to built these xml-structure manually by doing a (nested) loop through your source-table and store this result as output.xml (txt). But this will need some efforts to build a valid structure - but you could start with something like this:
When after exporting the table the xml-structure don't fit exactly to your requirements you will need some manually adjustment-steps maybe with a load-loop-statement like above mentioned. But maybe you could as an alternatively also adjust the target from the xml.