Minilogin authorizes by ip, basically if you don't want a computer to be able to sign in just make sure its ip isn't in the miniloginaccounts.ini, when the computer connects to minilogin it looks for the ip, and if it finds it is uses the username and password next to it to access the world server, so unfortuantly you can't make passwords as such. Just accounts specific to a machine, to change what account that computer logs onto you have to close off minilogin and world etc, edit the account file and start it all off again.
