To play as Vulture first you have to beat the game Ten times with all of the alternate costumes of Spider-Man.Then on the last level where you fight the Green Goblin You will be Alex Ross Green Goblin.Then you beat the game and watch the ending movie.Instead of Goblin dying it will be Vulture dying.Then you start the game and it says you've unlocked a new costume Start game to see it.As vulture you can fly and shoot those dangerous razor wings and you can fight all of the bosses without them ever attaking you.
(Note:You cannot ever be Spider-Man again if you do this.)Also you have to beat the game with every alternate costume even the secret cheat ones ten times each to get vulture.