Our downtown access point (downtown-ap.mmto.arizona.edu) is on our 192.168.100. subnet (so needs a special route to get to it from the wired subnet). It uses MAC address authentication. You add MAC addresses via the web interface; you will need the usual root password, user "admin", then use the "filters" selection, poke a new mac address into the entry fields and hit some sort of logical, but not immediately obvious button and there you go, it adds it to the list.