WHOO HOOOO! It worked! Here's the youtube link to the way to do it.
https://www.youtube.com/watch?v=MdMMqEcKwz4
First download the files from https://usa.yamaha.com/products/musical_...ml#product-tabs
Then install the Expansion manager in your computer. The rest was easy ... a bit time consuming, but follow the video, and it's simple. I now have 8 banks of Genos audio styles loaded in the SX900. The packs I installed are in the picture of the YEM. SUCCESS!

BTW - I found similar titles (ie: Canadian Rock) that sound much improved with audio instruments added. (duh) Haven't gone through all of them, but so far, only one swing style had a weird ride cymbal thing going on. I'll test them all out later today, and report as I learn.