Another thingy, i made once a while ago:
You can have a script only installed on the server, where
you gonna compare their playable unit's names versus the
manually filled list of possible admins. If one or more names
match, you can do further stuff then.
You need to check for the correct use of path names, when
executing the script (i need to have a look onto my ACS when
back home from work how exactly it has to be);
it's either: \missions\scriptname.sqs
or: missions\scriptname.sqs
or: missions/scriptname.sqs
or: /missions/scriptname.sqs
i can't remember exactly right now
You will need an array of all your playable units, and you will
need an array of all possible admin names.
Also you will need to check that the script will be only executed
on the server, to ensure nobody's getting a strange: "xx.sqs" not found error.
I've been using this technique for ACS (anti cheat system), and
i could succesfully determine, who has got rights to open up
a dialogue and who not.
The good thing with scripts only existing on the server is:
nobody else than one with direct server access can hack them
+ you can manually alter the admins list, while the game is running
+ you could even do that with all scripts, running on serverside
only (to improve network traffic).
:last one is a bit off topic for your situation
~S~ CD