A mIRC nick alert script,
it will make a beep sound, and open a new window, displaying all the nick alerts you've recieved.
on *:Text:*your_irc_nickname*:#: {
  window @NickAlert
  aline @NickAlert $remove(( $time ), $chr(32)) 12 $nick  nick alerted you on 7 $chan  saying: 12 $1- $+
  beep
}
Put that in the 'Remote' tab in mIRC (you can press ALT+R).
If you want this to exclude a certain channel, simply do:
on *:Text:*eDiT*:#: {
  if ($chan != #channel) {
    window @NickAlert
    aline @NickAlert $remove(( $time ), $chr(32)) 12 $nick  nick alerted you on 7 $chan  saying: 12 $1- $+
    beep
  }
}
Enjoy!
edit: fixed the if function