Airport lockout?

[thedigitalfox]

I have an airport network that I administer, and I can't seem to figure out how to dynamically create passwords and force the airport extreme and the WDS system to automatically change its password on a timed interval, or have a master password that would allow users to access the airport, and then have an additional password set that only lets users onto the network for a limited amount of time. I need to lock certian people out of the sytem, and allow others in, and also be able to create passwords that expire in 1,2, or 4 hours. Is there a way to do this? If not, are there any programs that would let me do this type of thing?