you might be able to use ifconfig. I don't have airport, so I can't experiment, but it might go about like this:
run "ifconfig -a". Keep the output
turn on airport
run "ifconfig -a". One of the interfaces that was in state 'down' before will be 'up' now.
Say that interface was called 'ap0':
run "ifconfig ap0 down" to bring down airport, or "ifconfig ap0 up" to bring it back up