It's not easy to script at all, in fact it is near impossible. The only (portable) way to tell who on a channel is away is to /who #channel every 1-2 seconds. On large channels, this will lag you incredibly, and it could also possibly cause you to be flooded off the server. Thinking about it quickly, regardless of whether scripting is used or it is directly done in mIRC, either way, it really can't be done.
