Turning my Yamaha digital into an .instru

This seems like it should be easy, but I've scanned the topics and haven't found it. I have a digital yamaha that I want as an instrument option in MS. I can record the audio, but of course this isn't as good as a direct digital transfer like when I plug it into the speakers of my computer etc. Is there someway to directly record that piano electronically? I.E, I don't want to record it with a microphone, I just want to plug it into my ipad with Xewton and press each note for a new instrument.