In Panther, it is now possible to configure an AirPort device from a machine connected to it via Ethernet bridging. Prior to this, you had to have an Airport-equipped Mac in hand to do this via AirPort Admin Utility.
Unfortunately, it is still not possible to cause the Airport device to disconnect which is usually done through the Internet Connect application.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031108162527324