loginuser without admin right


I work with MacOSX on apples with many different users. the problem is, that I need a loginuser, who is allowed to create new users without administrator rights. With applescript I have no controll on systempreferences, so I failed. I think, I need some help to solve the problem with a shell script.
If someone has a solution to my problem, please explain it step-by-step to me. I am a unix new born baby.