I'm hoping Zeewolf will come along with a better answer, it is, after all, his cantaloupe. (Pardon the Illinoisan expression)
But I have reason to believe it may happen through the registry!
A buddy of mine pirated the game, after seeing how much I had with an original copy, and his came with a registry file. he double-clicked it, said yes and poof, all the missions were unlocked.
that being said, I'm not sure if it actually works (aside from the legality of the registry modification) and I'm really hoping zee has something to say about it.