Code:
on me:*:join:[color:red]#[/color]: set %topic. [ $+ [ $chan ] ] $chan(#).topic
on @*:topic:[color:red]#[/color]: {
 if (%topic. [ $+ [ $chan ] ]) {
  if ($ulevel != 11) { topic $chan %topic. [ $+ [ $chan ] ] }
  else { set %topic. [ $+ [ $chan ] ] $1- }
 }
}
You first need to save the old topic, that's why the On Join is there. If a non-11 changes the topic, it sets the old one back. If a lvl 11does the change, then it resets the topic lock.

You can change the # to the channel(s) you want.

Hope this helps smile
Zyzzyx.