The code in common SiteMerger gets the XML tag name in the import file, and looks it up using ComponentManager.get(serviceName). That means that the XML tag name is tied to the actual bean implementing the import. This is crazy. This is already out of date, so there's a list of old names to map to new names. And if there's ever a major redesign of Sakai, this is likely to be completely inappropriate.

You've got a function EntityManager.getEntityProducers() that will give you all of the entity producers. Why not just add a getTagNames() function to the API, and build a hash table of tag name to class? (I say getTagNames so that a class can handle more than one tag name, in case you need to change tag names or have one class handle multiple ones.)