I finally did pay for this...
I posted on elance.com stating that it was PB 12.5 Classic project and found someone who knew enough about XPS to tell me that he could help me if I generated JSON string from the datawindow whatever that is.
We settled on me passing XML via: xml_string = dw_1.Object.DataWindow.Data.XML
I sent him a copy of the PDF file that I was generating and he created a replica of it 'somehow' and wrapped it up in a .net assembly that I was able to use in my project.
More of a hassle and more expensive than what I wanted, but I met the deadline for my client.
Paul
string xml_string
string imglogo
#if defined PBWEBFORM then
filepathname = MapVirtualPath("c:\TMS Receipt For-" + lname + "-Confo-" + voucherconfo + ".xps")
imglogo = MapVirtualPath("c:\!tms dev\online_receipt - 12.5\tms_small.jpg")
#end if
xml_string = dw_1.Object.DataWindow.Data.XML
#if defined PBWEBFORM then
//call XPSService .DLL which creates and writes out the XPS document
XPSService.GenerateXPS objXPS ;
objXPS = create XPSService.GenerateXPS();
objXPS.GenerateXPSFile(xml_string, imglogo, filepathname);
#end if