See iim.conf File Syntax for instructions on locating and modifying iim.conf.
Edit the iim.policy.modules parameter by setting it to one of the following:
iim_ldap (default, the access control file method)
identity (the Access Manager method)
If you choose identity, you can run imadmin assign_services to assign Instant Messaging and presence services to existing users.
Edit the iim.userprops.store parameter and set it to either:
ldap (To store user properties in LDAP.)
If you choose ldap, you can run imadmin assign_services to add the required objectclasses that store user properties to user entries in the directory.
file (Default, to store user properties in files.)
Save and close iim.conf.
Refresh the configuration.