I was wondering, is there such an option for mIRC?
Yes, mIRC supports this as a built-in feature. If you right-click on a channel's switchbar button, or click on its channel window icon in the top-left corner, or press alt - (alt+dash) from the channel, you will get a popup menu with an "Events..." menu entry. That entry opens a dialog with per-channel settings for all those events.
