If anyone is interested in this topic, here's the email response I got from Yamaha, which is about what you'd expect:
"Unfortunately there is no file for the 9000PRO. XG Works came out before that unit was around, and since they aren't making a Windows XP version of XG Works, there will probably not be more intrument definition files either. Sorry about that.
YCA Support
> Summary of problems/question: I own a Yamaha 9000 Pro keyboard and I just bought a copy of
> XGWorks, which I've upgraded to v3.07. When using Model Setup in XGWorks
> to select my instrument, there is no setting for the 9000 Pro. The
> closest setting is for the PSR9000, but that setting does not list many
> of the 9000 Pro settings and does not allow you to select editors for
> plug-in boards. If there a 9000Pro.ini file somewhere for XGWorks ?"
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Esh
http://www.mp3.com/esh