Migrate ER into a field collection

Well lets say you have a field collection and that has two fields, one term field and one ER field for a node. How to migrate the ER inside a field collection.
Field collection has migration see: http://drupal.org/node/1175082#comment-6801068

//into the fiel collection "field_collection_word"
    $this->destination = new MigrateDestinationFieldCollection('field_collection_word', array('host_entity_type' => 'node'));

Do i need to pre import the ER data? Is that even possible without loosing the wanted field collection grouping?