From mangos

Start up MaNGOS:

$ ./mangos-worldd

At the prompt type 'help account create':

mangos>help account create
CLI command under processing...
Syntax: .account create $account $password

Create account and set password to it.

Create an account:

mangos>.account create foo bar 
CLI command under processing...
Account created: foo

For additional features type 'help account set':

mangos>help account set
CLI command under processing...
Command set have subcommands:
    addon
    gmlevel
    password

mangos>help account set addon
CLI command under processing...
Syntax: .account set addon [$account] #addon

Set user (possible targeted) expansion addon level allowed. Addon values: 0 - normal, 1 - tbc, 2 - wotlk.

mangos>help account set gmlevel
CLI command under processing...
Syntax: .account set gmlevel [$account] #level

Set the security level for targeted player (can't be used at self) or for account $name to a level of #level.

#level may range from 0 to 3.

mangos>help account set password
CLI command under processing...
Syntax: .account set password $account $password $password

Set password for account.