How to host live chat?

I'm developing a website for a community. I'd like to host now and then a special event chat, where we'd have a special guest who we'd interview. Of course, we don't want everybody to talk at the same time, therefore have an option to mute everybody except the selected interviewers and the special guest.

Any clues as to how I could have this kind of chat on my site? I've searched and come across many chat programs for websites, but none of them had this option to mute a certain group of users.

I thought about doing it irc then, but have not really a clue how to program the irc into my site, so that visitors would not have to worry about the complicated functions.

Any insight, suggestion or help will be greatly appreciated.

/felipao