call wdw dining and PS garden Grill and tell them you want the rehitchin ceremony....like belle said, at first they treat you like a regular customer (hubby had no idea what was about to happen to him, he just thought I wanted to eat there because of characters and that the resteraunt rotates) and then u are suddenly on display...but its good fun and hubby even enjoyed it. This was his first time to Disney, we went w/o kids and he was like a big kid, he took pictures with every character he could find!
Anyway, you have a quick "ceremony" and you get a certificate signed by Mickey, and a free "cake" It ws good, but its pretty big, we only ate a small piece each because our lunch was so filling.