Hi Garth,
At the moment it is not possible.
Adding page numbers (and headers / footers) would require writing a layout engine. AFAIK, right now there is no open source layout engine. Without a layout engine, one can’t do pagination. Without pagination, there is no way to determine the page number, etc.
In the document, there are w:lastRenderedPageBreak elements. Unfortunately, there are ‘bugs’ in Word that cause these to be put into the wrong places in a number of circumstances. I put quotes on ‘bugs’ because Word does not guarantee the correct placement of these elements, so Microsoft doesn’t consider these to be bugs, I believe.
So currently, there is no good path to do this.
Best, Eric