If you use the xOP system on that channel just simply add everyone to the AOP list, that way no one can add anyone else .. only the founder and SOP's can add other users.
If you use the levels system add everyone to the same level that is required to add other users. In levels, you can't add users to the same or higher level that you, so if every is at the minimum level needed for ops, then no one can add other ops.
In either case, no modules needed.