Non-chromatic glissando

Love the new glissando playback, but there doesn't seem to be a way to get a glissando that isn't chromatic (i.e. glisses in the key signature without playing every single note in between). I'm trying to write for harp. The notation isn't a problem because what I want is the default way of playing it, but the playback version is intrusive and I'd kind of like to hear it the way it should sound.