Log in as the user or group under which Calendar Server is running (such as icsuser and icsgroup) that was specified during installation, or as root
If you want this attribute change to be recognized immediately, stop Calendar Server. Otherwise, you do not have to stop Calendar Server.
Change to the sbin directory.
Use the csattribute add command to add an attribute to a user or a resource. For example, to add the LDAP attribute icsCalendar with the value Conference_Schedule to the user tchang:
./csattribute -a icsCalendar=Conference_Schedule add firstname.lastname@example.org