Administrator on a Domain Controller in AD problem !!!

Hello,

I have a customer where we have 1 Domain and 2 Sites. One of the sites
has only one
Domain Controller. We don't want the administrator over there to
completely administer the AD. So we made a group for them and give them
the appropriate rights on the site.
Problem is how can you be an Administrator on a Domain Controller when
you are not
a member of the Domain Admins.

I have made a OU and placed the server from there Site in it. Then
made a Group Policy on it and gave Local login rights and more. But
still I can't find an option to just make that group an Administrator
on that particular server.

On a Member Server it is easy you just add the group to the local group
administrators on the machine. But on a Domain Controller that is of
course gone.

Help would be much appreciated.

Maarten Wensveen
Techsupport