I managed to make hardware mods for real-time AIR LED handling on WL500GP.
With my modification AIR LED could be turned off and on with "wlc radio 0"/"wlc radio 1".
I've tested it with original WL-120G V2A.
I don't know if the same fix will work with Atheros cards (maybe with Atheros you need only to move resistor from R107 to R108 instead of using inverter).
http://imajr.com/Original.aspx?Id=wifi_led_mod2_410465
