chatbox permissions - see/write

Hello everybody.
I hope I posted in the correct section, the "general support" was not accessible for me.

I am still building up the forum I need and I would like it to have a chatbox with customizable permissions.
I'm going to create 1 extra group,  with normal user permissions,
but to be explicitly approved by moderators, wich will see and write in reserved sections.

I need the chatbox to be visible (and usable) only from that rank up, not to normal "registered users".
Is it possible?

This is the major priority so I don't really care the forum to be in phpBB2 or phpBB3,
I'll take every suggestion.

I tried to look it up on the FAQ and on the tips ancd tricks, but I found nothing.

The one thing you can do, is make it a chat box moderators duty is to ban every single user besides those who deserve to join the chatbox. If they cannot do it, tell them that you'll hire someone else for the job.

I do not see an option in the chatbox configuration area for such a thing. This is the only solution I see.

closest way to prob do this would be to

set chat display to do not display
then put it on the portal page useing a widget and set the Rights