Add file name and "page x of x" to bottom of documents

I am working on making the bottom center of thousands of document look like the below example.  It can be done with a footer but the bottom right corner is already taken so it has to be spaced in the center.

I need this to be automated in the Action Wizard, here is what I have come up with so far and it successfully adds the name to the bottom center but I cannot seem to figure out how to add the page x of x for each document separated by a comma.

event.target.addWatermarkFromText({
cText: event.target.documentFileName,
nFontSize: 10,
nVertAlign: app.constants.align.bottom,
nVertValue: 18
});

app.execMenuItem("Save");