cd ~
tar xjf compat-wireless-2.6.tar.bz2 (asuming you have downloaded comapt-wireless form the link provided)
cd compat-wireless-2009*
make -j4
make unload (root)
make install (root)
echo options iwlagn swcrypto=1 >> /etc/modprobe.d/options (root)
make load (root)