Dear John,
I haven’t tried to do this. My first experiment would be getting the XML created. Open Report Style, choose default SSRS style and choose Actions / Copy Report Style. Then change output from database to XML. Save your new style, open a PO in PO Tracker, and print it, manually choosing your test style. Remember that in Epicor 10 (at least on our server) the output XML directory may not be the same as that of log files.
I’m afraid I don’t know how to change the source of SSRS reports, but it may be possible when you open them for editing, to change their data source to your XML file.
Best
…Monty.