Check out this thread.
hey, i am trying to use BackTrack 4 but don't have a USB wireless adapter. I have plenty of wireless routers and was wondering if instead of using a wireless USB adapter i can use a wireless router(maybe in client mode) as the wireless adapter. how to configure the router to work on Backtrack 4 as a wireless adapter or what to configure on BT4 to recognize the wireless router???? Is there any way this is possible??