You have 2 interfaces:
 - wifi0 - represents physical hardware
 - ath0 - the 802.11 interface.

Sequence to get continuous transmition working:
 # being down ath0 interface
 ifconfig ath0 down
 
 # setup desired frequency, rate and txpower on ath0 interface
 iwconfig ath0 channel 50
 iwconfig ath0 rate 54M
 iwconfig ath0 txpower 20

 # load ath_txcont module
 insmod ath_txcont
 # if you have more than one wifi interface, you can specify it via device parameter
 insmod ath_txcont.ko device=wifi2


 # being up wifi0 interface
 ifconfig wifi0 up

 # Vualia, you have continuous xmit working.
 # To stop ir - bring wifi0 interface down.
 # and remove ath_txcont module
 ifconfig wifi0 down
 rmmod ath_txcont

NOTES:
 * depending on Your system, you may have not ath0, but let say ath5, or other ethX.
 * Be sure, that NetworkManager is not configuring Your interfaces. Before 
 starting continuous transmit - disable network manager to control wireless interfaces.
