???

Hey guys, I need some advice!
I am not posting this on Facebook because I want to keep it "in the family." I have a co-worker who is a truly good guy. Caring, hard-working and would do anything for you. The problem is, his position at work is in administration but not in a supervisory role. Actually that's not the problem, the problem is that he conducts himself as though his position is one of supervision or authority and that causes lots of resentment from those working with him.
For instance, we have monthly meetings. Part of his job is to report off on data submitted to him by clinical people (he is not clinical.) During the meeting, instead of simply reporting the data, he will say things like, "I don't know what's going on with Department X. You guys are having some major issues. " Or he'll come to our morning meeting and announce that "You guys have to get such and such information to me immediately."
And my favorite, "I know you don't want me to have to come and talk to you!"
When relationships with co-workers are less than supportive and cooperative, he gets hurt and therefore, that much more demanding.
During a meeting today, he stated that he had authority over the nurse managers to require them to do things a certain way. Well guess what, he doesn't. Therefore, trying to get things done in the name of imaginary authority, he gets less cooperation than if he just learned to be one of the team.
I don't know if I'm making any sense but I need some feedback. I like this guy, I consider him a friend. But even I want to poke him in the eye most days. Because I'm his friend, I think I'd be the most gentle and supportive trying to help him improve his demeanor. In fact, the boss (who actually is the boss) wants me to have a conversation so he doesn't feel attacked but does get pointed in the right direction.
How do I tell someone they aren't the boss and so they need to stop acting like they are and start building relationships based on trust and respect? I think he wants to have a position of authority but it just isn't going to happen in a health care setting because he is not a doc or a nurse.
Help!