Ummm..I don't think OS X will work with a 6500.

http://eshop.macsales.com/OSXCenter/XPostFacto/Framework.cfm?page=Compatibility.html

It says there are lots of problems and I don't think OS X recognizes the G3 upgrades for those models. Look for my thread about installing Tiger to a 603/604 machine. I think that might work better than an Xpostfacto install, but I still don't know if it will utilize the G3 upgrade.