How many are you printing and what size? How are you printing these? Yourself or with a printer/copy shop?
Are you using the Print Booklet feature directly from ID? or printing PDFs from Acrobat? etc etc.
If you are not printing these yourself, many printers have ways to add variable data like this to print jobs. Check with them as to what's possible.
If you are printing these yourself, depending on how many you need to print and how often, there are ways to add numbers in Acrobat, or you might look at a software solution. I personally like the look of one called NumberPress. Depending on how often you do this, something like that may be worth the price.
As for an ID approach, I don't know of any easy way myself, but others will jump in I'm sure.