My old Yamaha keyboard does support user Style files, but only in midi, not audio unfortunately.

Ableton software, Melondyne etc, have the ability to convert an audio file into a midi file interpretation. That kind of function in BIAB would be perfect. I could then compose a small 16 bar arrangement using realtracks for example, convert it to midi, then process it into a Yamaha Style file to use as an onboard user style on the keyboard.