Start by updating and upgrading BackTrack as usual.
apt-get update
apt-get dist-upgrade
When comes to kernel updates, typing "n". Next, install drivers as needed and kernel sources:
apt-get install madwifi-drivers broadcom-sta r8187-drivers linux-source-2.6.34
apt-get clean
depmod -a
Last, prepare to update kernel sources:
cd /usr/src/
rm -rf linux linux-source-2.6.30.9*
rm -rf /lib/modules/2.6.30.9/
tar jxpf linux-source-2.6.34.tar.bz2
ln -s linux-source-2.6.34 linux
cd linux
cp /boot/config-2.6.34 .config
ln -s /usr/src/linux /lib/modules/2.6.34/build
make scripts && make prepare
apt-get clean && updatedb
reboot # dont forget to reboot!
Complete!