Maybe Logic Pro X could be used this way to make custom midi tracks that can be imported into the new Korg Pa4x built in SMF (Standard MIDI File to Style converter). I don't know if it would be easier to make your own custom styles onboard the Pa4x hardware, it's editor, or import them via the SMF method because I don't understand enough about the Pa4x yet. I'm talking about self-made custom styles from scratch, not taking existing pop song cover MIDIs and importing them.
Hal
Thats probably the best way to make styles... As styles are in the end nothing but a bunch of midi tracks...
Withnthis tool you can export your drums as a midi track...