Last time I did an external (a too long time ago), I gave the newly compiled external a new, unique name, like myExternal023 and could instantiate it once I double-clicked on it.
With XCode, I'm not even sure I would find where to edit this name ;-)
I think Peter Castine (Peter, where are you?) once wrote on the mailing list he had another, of course more handy, technique, but I don't remember which one...
p