Steve,
You may want to look into the "-command" command line flag. It allows you to suspend a server:

sesame -command server_name password SUSPEND

This will prevent any new connections and prevent that server from accepting commands until you issue a continue command:

sesame -command server_name password CONTINUE

The "-command" flag can also issue load and unload requests so as to "freshen" a particular application. Of course, should any of your users have that application open at the time, they should probably close them and then reload them after you are done.