I usually use a cable modem for net access, however, I was out of town this weekend and installed OS X on my Powerbook.
Network control panel was set to no connections. I then was able to use PPPConnect to connect to an Earthlink acount. I entered all settings manually.
One problem I had at first... OSX was using PPPConnect while my OS9's settings were still using ethernet. I could connect to nothing with classic... once I figured this out and set tcp to ppp in classic, all worked well.
Now I am back home and switched both back to ethernet and all still works fine.