First create some temporary directory like:

Code:
mkdir ~/tmp
cd ~/tmp
Download madwifi hal driver:
Code:
wget http://snapshots.madwifi.org/madwifi-hal-0.10.5.6-current.tar.gz
... and extract it:
Code:
tar zxvf http://snapshots.madwifi.org/madwifi...current.tar.gz
Go into source directory:
Code:
cd madwifi-hal-0.10.5.6-r3861-20080903/
... and run:
Code:
make
sudo make install
sudo modprobe ath_pci

Enjoy!