I'm trying to create a SQL data and metadata that manages employees that have inetOrgPerson, shadowAccount, posixAccount and sambaSamAccount. I have an LDAP_PERSON table with the columns for the attributes on those object classes. How do I populate the ldap_oc_mapping table?

This is entirely dependent on you data and database-of-choice. Views tend to be very useful for this; check out http://docs.opengroupware.org/Members/whitemice/OGo-Back-SQL/ogo-back-sql-cr... for an example of how to use fancy SQL to automatically map a complex schema.