Currently, it's impossible to do this, because Neologism would check that a vocab is served from the "Namespace URI" (not the case here : http://schema.org/ )

Trying to fool it passing it another URI (such as schema.rdfs.org RDF file) does not work either because the namespace URI does not match the base URI used in the file...

(So trying to enforce good semweb behaviour becomes a bug where it was a feature...)