About root user rights

[Halid Faith]

I use Freebsd6.0.stable.
 
Let me explain my scene.

I am an admin for my bsdserver. That is, I can be root user. But There are 3 people who can be root user in the same server.
I have a directory. I want them not to enter that directory. if it be possible the server should ask one more password for that directory when anyone reaches there.
Or let another user can reache there but let "Root user" not able to read there. Does it possible ? 

Thanks