This question recently came up in the pa80 group. And we're lucky enough to have some Korg reps participate. One of them, another guy from Italy named Andrea (not you, Dreamer) has said that the Korg people use the same MIDI to style software that they have made available to us meager customers. It seems hard to believe, but this is how they create factory styles, but at least at Korg, that's how it's done.
Tom G.