Although these are subject to change, the current schedule is:

December 24, 2006: 8-9pm, 10-11pm EST
December 25, 2006: 12-1am, 6-7am, 10-11am, 2-3pm EST

NOTE: This is the EST broadcast schedule and actual broadcast times change based on the time zone of the viewer.

Of course, the best thing to do is to check local programming schedules if you want to catch it.