Copy this snippet, then in your mIRC, click "alt R", goto "new",
then paste this code and then "save as" and name this "Op Thanker".
To enable/disable, simply right click in channel, and select and click "Ops Thanker". It's very simple!

#opthanks off

on *:rawmode:#:{
  if ($2 == $me) && $istokcs(v h o a q,$right($1,1),32) {
    if (+ isin $1) {
      %mode = " $+ $replacex($right($1,1),v,+v,h,%,o,@,a,&,q,~,oa,&,oq,~) $+ "
      msg $chan Thanks for the4 %mode $+ , $nick
    }
  }
}

#opthanks end

menu channel {
  Ops Thanker ( $+ $group(#opthanks).status $+ ): {
    echo -a Ops Thanker $iif( $group(#opthanks).status == ON, Disabled, Enabled)
    $iif($group(#opthanks).status == on, .disable, .enable) #opthanks
  }
}