Here's a video giving detailed instructions on how to activate the Easter egg.
This player, however, doesn't know how to fight zombies. Head shots, people, head shots! Have you learned nothing from my teaching? Unless you destroy the brain, the zombie will keep on coming back.
I recommend choosing the .45 Silverballer with the extended magazine, extra clips, and scope. Move calmly through the ship. Walk, don't run, unless you're surrounded. Make every shot an aimed shot. There will be 108 zombies on board (maybe less one or two -- sometimes not every person on board turns to the undead). Sweep methodically through the ship, deck by deck, until you get to the uppermost deckhouse and complete the mission.
There is also Hitman movie coming out in eleven days. Here's a trailer. It looks very fan-servicey: the text font, the music, and even the Eidos logo are straight from the game. The trailers suggest that the writers have altered Agent 47's character to make him more likable, and changed his background story.