Eh... This is horrible!
I made this example script on the spot, but I guess you get the idea of it...

on *:INPUT:#: {
  if ($regex($1,/(:?[+|-])(:?(\\w+))/S)) {
    if ($regml(2) isincs $remove($chanmodes,$chr(44))) {
      mode # $regml(1) $+ $v1 $2-
    }
  }
}