Try:
Code:
on *:text:!invite*:*:{
  if (!$1-3) { halt }
  else {
    var %passwords = password1 password2 password3
    if ($3 isin %passwords) {
      .msg Mrbot invite $nick $3
    }
  }
}


Course that is kinda choppy as if one of your passwords was "moo" and someone typed in moon it would allow it. Hrm, ill further explore. Hopefully someone will solve it before I will. Lots of smart merker's on here. I'm thinking regex would be good here.

We don't just write the scripts, we put them to the test! (ScriptBusters)