Tempown allows main owners to promote guests, members, and moderators to owner for any duration of time, up to 24 hours.
Temporary owners that are signed in while their owner rank expires will remain an owner until they sign out and in (including changing name, avatar, and homepage) or by attempting to use any moderator ability; such as banning, demoting, kicking or promoting. They will become a permanent member afterwards, or a permanent moderator if they were a moderator previously.
Temporary owners are not able to make permanent moderators or members. If a temporary owner attempts to make a user a member or moderator, they will instead make the user a member or moderator for one hour, even if the temporary owner does not have Tempmem or Tempmod. However, the temporary owner will still be able to use Tempmem and Tempmod. The maximum amount of time that a temporary owner can ban by default is 24 hours, however this can be extended with GControl.
Start a private chat with the user you want to make a temporary owner and type /mo followed by the duration of time you want them to be an owner for (in hours).
Example: Sending /mo12 in a user's private chat would make them an owner for 12 hours.