Ebook Central does not currently support XML gateway or Z39.50 for federated search. It is being considered as a future enhancement.
If your organization would like to request support of this format, please send an email to firstname.lastname@example.org.
For federated search, Ebook Central will eventually support eXtend API. It will be straight HTTP with a simple XML return package for search results. The Ebook Central support team would just need to authorize the IP addresss of your search server.
In the meantime, if you had federated search set up on ebrary, it should continue to work even after your upgrade to Ebook Central. However, the ebrary federated search will only return search results for books that were on your ebrary site - not books added to your Ebook Central site post upgrade. The federated search links to ebrary books will redirect smoothly to your Ebook Central site.