I've done similar with a bot of my own, letting other ops run a backup that will join automatically if mine disconnects and then part when mine returns, though it's not enabled atm.
Here's one way to do it:
On person watching for bot getting disconnected:
on bot:quit: { .notice backup_bot_nick join #yourchan }
on bot:join:#yourchan { .notice backup_bot_nick part #yourchan }
On backup:
on watcher:text:join &:?: { join $2 }
on watcher:text:part &:?: { part $2 }
You can adjust how you want the command sent. I just did /notice to make it easy, but you can do a similar thing using /msg or /ctcp. You will want to add the hostmask of the bot to the "watcher's" user list with a user level of BOT. Then add the hostmask of the "watcher" to the backup bot's userlist with user level WATCHER. As long as the $address() of the watcher/bot match what you out into your Users list, the events will trigger. Make sure to use a mask that works best for your situation. For example, if the host changes often, you might want to use wildcards.
