Hi Drake,
I do not have the China pack for S650, so I am not 100% sure, but I guess it is not compatible with Genos. For older Yamaha arranger keyboard model(s) such as Tyros5, Tyros4, S650S750/S950 etc, he can install this pack. For newer arranger models such as S670/770/970/775/975/Genos, he cannot install this China pack for S650.
My experience with the China pack for S970 is that in order to install it on YEM, I had to add the keyboard with the S970 instrument information file on YEM. Once the China pack was installed for S970 on YEM, then I had to add Genos instrument information file on YEM. After that I was able to include the China pack in generating the Genos_PackInstallData.ppf (packs from Yamaha only) or Genos_PackInstallData.cpi (packs from Yamaha and 3rd parties).
The China pack for S970 is compatible with Genos because they both use SWP71 tone generator. PSR-S650 probably uses SWP51 tone generator, and so the China pack for S650 is unlikely to be compatible with Genos. This is the reason why Yamaha published the schedule of expansion pack conversion from Tyros5 (SWP51) to Genos (SWP71x2).
Thanks,
Paul