Granting Limited Admin Rights

We have created a forum node for a special project, and user group with rights to use that forum. It's working well.

I would like to hand off the task of adding users to the special user group to the person who is in charge of the project - he is not otherwise a forum admin. Is there a way for me to grant this user the right to use the ACP to add users to his group, take users away from his group, and that's it? He is already a moderator of his special forum. (Is there another way to add users to a group besides the ACP that I could give to this person?)

Thanks in advance.

I'm back - I still need this, and still don't have a way to manage it. I have a section of my forum that I want one person to be able to administer; I want him to be able to change group memberships, adding and removing people from the groups that control access to the forums in his area. But I don't want him to have admin rights other than that - he is already a moderator.

As it now stands, users PM me or him, or they post in a public section and ask for access to the closed area. My moderator gets my attention, I add the person, then I have to let my moderator and the user know the matter has been taken care of.

An add-on? I'm listening. :)