I know mIRC has some kind of way to read logs, but as far as I remember it doesn't really work so nicely if there's any kind of colour codes in your logs. therefor this. I find this works pretty well for, and it's really simple, as you can see.
alias logviewer { window -k0 @LogViewer | filter -cfw $qt($sfile($mircdirlogs\)) @LogViewer $iif($1 != $null, $1, *) }