Dear Tom,
I own a Clavinova CVP309 in polished ebony, and an actual Genos arranger, both beautiful instruments.
Your "Rolls Royce" was produced about the same time of my CVP309, if I'm right. Then I assume that its styles are in SFF1 format.
Yamaha styles are of two formats:
-SFF1 format, early keyboards including Clavinova CVP 409 and Tyros 2.
-SFF2 format, the one presently used
Any SFF2 instrument is able to load both SFF1 and SFF2 styles.
SFF1 instruments can only load SFF1 format (actually there are software able to convert SFF2 styles to SFF1 format).
I believe that you can load directly (no need of external software) into your CGP1000 any SFF1 style. This web site got PLENTY of them.
Enjoy...
Ciao
Angelo