Since InDesign takes the auto numbering from the page the item is sitting on, that would not be possible to just use auto numbering. However, I just tried somethine and it actually worked! I made a master spread of two pages. On the left hand page, I put a text frame with auto page numbering. On the right hand page, I made a small text frame with no text in it and put it outside of where my page items will sit (but on the page...like tiny in the lower right hand corner). Then, I anchored a text frame to that frame, told it to sit relative to the page margins and changed the offset so much, that it sat on the left hand page, right next to the other page number. Because it's anchored to an object on the right hand side, though...it gives it that page number...but appears on the left hand page! I simply played with the offset and the location of the left hand page number, until lined up. I also put a third text frame (on the left hand page) with the | character, made the left hand page number right-justified and the right hand page number left-justified to accommodate longer page numbers. Hope that makes sense...I have the InDesign file I made if you need it.
