Well, if you truly want to simulate the graphic novel, you should make sure to devote an entire session to one player's origin story. Then you should have a smidgeon of plot. Then you should repeat this cycle four more times. Somewhere in there, you should have the party disband, then partially reform. Two players should start with characters that are vastly overpowered that symbolically emasculate at least two other players. Two players should start with evil characters, a third should turn evil and a fourth should go cosmic disinterested Neutral. There should be two utterly kick ass fight scenes (no more, no less) but one should involve a grudge match with a villain the rest of the party has never met.
The campaign should end in bitterness, recrimination, tears and player v. player combat. And even THAT should all be for naught.
Watchmen: great comic novel. Perhaps not a good idea for a campaign. Still, best of luck, but consider my words for what to avoid.