You'll want to put whichever script you use in your Remotes (Alt-R, click Remotes tab). Make sure that you do File>New so that you don't have conflicts with any other scripts that are running.

Here's one that can work for multiple networks that have different passwords.

Code:
on *:NOTICE:*:*: {
  if ($nick == NickServ) {
    if ($strip(This nickname is registered) isin $1-) {
      if ($network == network1) { msg nickserv identify password1 }
      elseif ($network == network2) { msg nickserv identify password2 }
      elseif ($network == network3) { msg nickserv identify password3 }
    }
  }
}


Just change the network names and passwords and repeat the elseif lines to add more networks. If you don't know the correct network name, connect to the network and type //echo -a $network . That will give you what you need for the network name in the script above.