So we had an Xserve running 10.5, and the guy who set it up vanished with the admin password. We had to add more users, so here is what I did to gain access to the server.
1. Boot from the Mac OS X Server installation DVD.
2. Reset the passwords of both the administrator and the root account.
3. Restart the server and log in as administrator.
4. Type the following commands in terminal:
sudo mkpassdb -dump
5. Find the slot-ID of the diradmin account (it’s usually the number 2 slot)
6. Type the following commands to change the password:
sudo mkpassdb -setpassword [slot-ID]
The instructions to reset the password was found here. Thanks, Erik.