I've posted a long article in the developer blog about migrating from custom service management structures to CSDM. The ideal place for this article is in the CSDM forum but it's not suitable as a "question".
Link: https://www.servicenow.com/community/developer-blog/csdm-migration-from-custom-service-management/ba...
Hope it helps anyone working with CSDM in a custom environment!
Mat
