LiveCycle ES has an administrative console you can get at
http://localhost:8080/adminui. You can log in with administrator/password.
Under the Settings section, you can go to User Management and then Domain Management.
In there you can define a new Enteprise Domain and create a new Authorization and Directory for that new domain.
In the Authorization, you can select LDAP. Under the Directory, you'll be taken through a wizard that will help you configure the LDAP connection to get the list of users and groups.
Then go back to Domain Management and select "Synch Now". You can set that synchronization to occur periodically.
Once you can connect to the LDAP server properly and get the list of users, you should be able to log to the different interfaces using users from the LDAP system.
You might need to give them LiveCyle roles to access some of the interfaces like adminui, workspace, etc. You can add roles under Settings/User Mangement/Role Management
Jasmin