It is booked through the 407-WDW-DINE line or if it's available, you can book it at MGM on the same day. We booked it in advance by ourselves last year. WE LOVED IT! The food at Mama Melrose's was wonderful and it was great not standing in line for 2 hours to get a good seat at the show. This year, it was booked by the Concierge at the Beach Club. We are trying Hollywood & Vine this time.
Have fun!!