If you can get hold of a Xara Template that has page numbering (from a trial) then you can add that to your Template list and it will work.
Another opportunity might arise should a TGer have presented a page-number design in prior Threads.
So, if I understand what you are saying, but not saying, is if Kenn posts a layout of what he is looking for with an example, someone here could create a page he could use for the page number?

And if so, would this XAR file work in PGD?