My enfj friend is bipolar.
I room with her, but I wouldn't say she is much like your friend. She is just rather emotional at times and I don't understand how to help her. She can have the creepy ENFJ stare, but I just point out to her that she is being a creep, and she generally tries to stop.
Maybe just tell him straight up to his face that he is a bit odd, and you don't really appreciate it. If you must hang out with him, just avoid/ignore him while you are around him in groups.