I also have a newertech card it's a 300mhz card that I have running at 366mhz. I have installed osx and it works great. I first tried installing it on a PowerPC 8550 even though it a little slow you can see the joy of getting it to work on a 132mhz machine, and it hasn't bombed yet. Check this site out and it will tell you if it will work with your machine or not. Newer didn't finish making the drivers to install osx but this puppy works like a charm.
I tried the utility from Sonnet at $30 but it didn't work properly. But this one is free, completely free.
http://www.macsales.com
Go to the OS X Center on the drop down menu and you will find a utility that will allow you to install it. Good luck.