If you have an old (first generation) AirPort Base station that you need to reset, there are instructions on Apple's support site.
However, you'll also need a copy of the AirPort Admin Utility for Graphite and Snow.
Of course, this ends up not being enough, as there appears to be an endian issue when running the reset procedure on Intel Macs. A workaround would be to force the application to run under Rosetta, but the checkbox to do that in the 'Get Info' window was disabled when I looked. Fortunately one can use the command line program 'arch' to force execution of the ppc version of the application.
`arch -ppc /Applications/Utilities/AirPort\ Admin\ Utility\ for\ Graphite\ and\ Snow.app/Contents/MacOS/AirPort\ Admin\ Utility\ for\ Graphite\ and\ Snow`
Since there are plenty of cheap base stations available (often with significantly better features and faster wireless and wired support), there are probably very few people who are even bothering to use these old base stations anymore. However, there are a few cases where they are still useful, and that beats sending them to the recycler (or throwing them away).
I found that on an Intel machine if you quit the application, the Rosetta option is available. I still received an error when trying to re-configure the Graphite ... not sure why. I had to use a ppc to do partial reconfig, but I still cannot rename it nor set it up as a bridge.