There is an openldap in the CentOS Testing repo for centos-4 that will work with centos-5.
It has a compat-openldap-<c4_version> for the things that are compiled against the c4 version ... and i am using it in production and syncing c5 and c4.
This works great! Thanks for the tip, this is just what I was looking for.
However, it is a couple updates behind.
The version is openldap-2.3.27-4.el4.centos
This is the same version as CentOS 5, perfect.
Brett