in case of fresh install: import config-template.ldif (conversion, generation tools would be useful for package maintainers to update the config-template.ldif)
in case of upgrade: maybe we need a system of patches updating the modified parameters of configuration (patch-2.5.7to2.5.8, patch-2.5.8to2.5.9). The package would try detecting correct versions and applying the appropriate patches
cn=config should now be the default.