When we went 3 years ago, there were 26 of us in the group. We did a Wishes Fireworks cruise. I'm not sure of the exact name of it. But they had us all meet at the Contemporary (I think?) for a dessert buffet to start it. They had a room set up with several tables filled with all kinds of yummy desserts. Then a couple of pirates, along with Captain Hook and Mr Smee arrived and did pictures and autographs. Everyone got a Magical Gathering Fireworks Cruise pin. Then we went down to the boats. The pirates stayed on the boats with us (not Captain Hook or Smee). The pirates entertained us with pirate jokes, trivia and songs while we were cruising. Then we got to watch the Water Parade and Wishes from the lagoon. When we got back to the dock, Peter Pan greeted us and hung around for pics and autographs. It was a really fun evening!
I was not the one who organized it though. Someone else in our group arranged the whole thing so I don't know what she had to do to do it. I'm assuming just called the Magical Gatherings number and told them our trip dates and the number of people. I don't remember how much it cost either. It was expensive, but not unreasonable. Well worth it!