The prayer is:
Hail, and blessed be the hour and moment at which the Son of God was born of a most pure Virgin at a stable at midnight in Bethlehem in the piercing cold. At that hour vouchsafe, I beseech Thee, to hear my prayers and grant my desires. (Mention your intentions here) Through Jesus Christ and His most Blessed Mother.
The faithful are encouraged to repeat this prayer 15 times daily between November 30 and Christmas.
I'll be posting this prayer in my sidebar (based on Alice's idea) as a reminder to say this prayer.