S/MIME certificates in UCS OpenLDAP


are there any whitepapers or documentation available on how to store S/MIME certificates in UCS LDAP in order to have them automatically beeing available in mail clients connected to the LDAP (e.g. Thunderbird)?

So far I did not find any inofmration on that regarding UCS 4.4 and if schemata extension is needed and how this could be done.

Best regards,