There is a way to do it in 10.4.x from the command line, but I wouldn't attempt it unless I was very familiar with the command line. You may a little afraid to do it yourself, but here is the list of commands:
I can't take full credit for this. I found it at:
http://farbflash.de/cgi-bin/blosxom.cgi/?find=snippets
The commands necessary to create an admin user are as follows:
sudo -s
niutil -create . /users/username
niutil -createprop . /users/username passwd \"\"
niutil -createprop . /users/username home /Users/username
niutil -createprop . /users/username shell /bin/tcsh
niutil -createprop . /users/username uid 520
niutil -createprop . /users/username gid 20
niutil -createprop . /users/username realname \"First Last\"
***if this property is not created, the user won't appear in the loginwindow!
***
niutil -appendprop . /groups/admin users username
***only for admin users!
***
These below are optional:
niutil -createprop . /users/username hint \"password hint\"
niutil -createprop . /users/username
writerspassword username
niutil -createprop . /users/username
writershint \"\"
niutil -createprop . /users/username
writerspicture username
niutil -createprop . /users/username sharedDir Public
exit
There needs to be a valid home directory, shell, and/or SharedDir for the user. A home directory can be created as easily as:
sudo mkdir /Users/username
sudo chown username:staff /Users/username
Or if you want the default OS X user directory structure:
sudo cp -rp /System/Library/User Template/English.lproj /Users/username
sudo chown -R username:staff /Users/username
***(/System/Library/User Template also has other localized language templates)
***
Additional info:
To change an admin user back to an ordinary user:
sudo niutil -destroyval . /groups/admin users username
Be careful to leave at least one accessible admin user, otherwise you will lock yourself out of your machine.
after changing netinfo:
sudo niutil -resync .
log out and in the user you changed.
