You need to use the mIRC scripting language. For this, you would use the ON TEXT event which triggers when someone says something in the channel.
E.g.
on @*:text:!rules*:#your-channel:{
.notice $nick The Rules are as follows:
.notice $nick 1) No doing this
.notice $nick 2) No doing that
.notice $nick 3) And so forth
}
This triggers only if you're opped in #your-channel. It will send 4 notices so they are in a list. You will not see the notices being sent on your screen because of the . used, if you removed the . then you'd see the notice being sent.
This code, and most scripts in fact, go in mIRC's Remote of the Script Editor - press ALT+R to access it.
For further help, see /help on text.
Regards,