I belive that OS9.1 has support for printing over TCP/IP. You'll need to enable that. I'm not sure which screen you use for that, but it's probably one of the relevant Control Panels, such as the TCP/IP control panel.
Once you enable TCP/IP printing, you should be able to see the Phaser 6280 using the LaserWriter (Postscript) driver in the Chooser.
Your network hardware media is ethernet, but the protocol you're trying to use over the ethernet hardware is AppleTalk, and the Phaser 6280 does not support AppleTalk. You need to use a communications protocol which both OS9.1 and the Phaser support. And that choice would be TCP/IP.
A couple of years ago I was shopping for a printer and was extremely tempted by the Phaser 6180 with it's affordable price, built in ethernet, and Postscript support. But I also needed support for older Macs, going back to OS 7.6.1, and I noticed that Xerox had dropped AppleTalk support over Ethernet, so I went with a different brand.
I don't know why they dropped it. The code was already written. Why not leave it in as a legacy network protocol which is supported -- or even unsupported but present.
If you can get the printer to show up in Chooser you can configure it as a generic AdobePS printer or Laserwriter since there is no PPD's available.
I don't think this model comes with AppleTalk so this may limit the connectivity.
Alternatively, you may be able to setup the Laserwriter printer to send jobs via LPR if you have your mac and printer configured with TCP/IP.
I have an old Mac which uses OS9.1 that I need to print from which has old graphics software I can't convert to current technology. Is there any possible workaround to printing to the Phaser 6280 from it? The chooser just doesn't see a postscript printer when clicking on "Laserwriter 8" which is how I usually print generically. I don't want to upgrade to OS X on that machine due to software that won't upgrade.
I know I'm pretty much grasping at straws, but figured I'd give it a try anyway...