Given OpenLDAP uses standardized schema formats , I suggest you ask the application developer to provide you with their schema descriptions in standard format (RFC 2252). Conversion of standard descriptions into a slapd(8) configuration file (either slapd.conf(5) or LDIF for cn=config) is trivial.
If the application developer cannot provide their schema in a standardized format, I would suggest you question their commitment to open standards.
Frank