Assign post author to any user

In short, I'd like to log into Wordpress admin (3.0.1, no MU or Buddypress) and create a post on behalf of another user. However, I don't want this user to have publishing privileges.

I feel like this is any easy hack such as overwriting the post_author_meta_box() function, but I can't seem to figure out how to get a list of ALL users instead of getting a list of those users who are capable.

Hopefully that made sense. Any help on this would be excellent. Thanks!