Then why would they have submission guidelines the unwashed masses can find? For shits and giggles? One would think they would come right out and state "no unsolicited submissions/agented work only" if that was all they accepted.How is this done?
Long answer short, it isn't except by invitation.
Long answer a bit longer, it isn't unless except by invitiation or very remotely possibly, if you have an MFA from the right university AND the right agent AND know the right people AND are already a feature on the NY literary scene.