Looking at the Xfinity website, they're channels 500-504 in the Philly area. Other than Wrestling and UFC matches, they mostly show porn.
Huh, thanks. Did not know that. The harried CSR on the phone pursued an answer, but all I could make out was "enter code" and "remote".
Fortunately, the Comcast website's automated email help did eventually respond with the following (highly edited by me), for anyone's information:
Customers can order either using their remote control, or by calling 1-800-COMCAST.
As soon as a you tune to a PPV event, you will be billed for the event.
If you order a PPV event prior to the start of the event, you will not receive an order confirmation screen. To confirm that their order was processed correctly, they should access the event's information screen. To the right of the date and time of the event, a '$' will be displayed.
You will only receive an order confirmation screen if the event was ordered at the time the event starts, or after the event has started.
For Special Events:
1 Press the Menu button on the remote control
2 Select Main Menu from the quick menu
3 Select Pay-Per-View Events, then select HD Pay-Per-View Events or HD Pay-Per-View Events (note: only HD set tops will have an option for HD Pay-Per-View Events)
4 Make a selection from the events listed and press the Select button
5 Select Buy or Watch for the selected program
6 Confirm the selection and enjoy
For other Pay-Per-View Programs:
1 Select Guide on the remote control
2 Scroll to the Pay-Per-View channel listings
3 Highlight the Pay-Per-View program and press the Select button
4 Select Buy or Watch for the selected program
5 Confirm the selection and enjoy
Sounds easy-peasy, actually. I also noticed that Pay-Per-View access was explicitly listed as a feature of "Digital Economy" on the price sheet included in my latest bill, which just came the other day.