welcome to WebmasterWorld, bkoo004!
it's going to be difficult to find an answer here for such an unusual configuration.
i would assume you started here - mod_auth_cas - CAS Clients - Jasig Wiki:
and perhaps this has some configuration details you may ultimately need - LDAP - CAS User Manual - Jasig Wiki:
i can't help you at all with Zope, but perhaps this all-apache config can give you some clues - CAS authentication and LDAP authorization: