[ I put a much simpler fix for this in the thread Problem with BCM4318 wireless LAN on Acer 5300 ]

(I could be wrong, but getting an updated version worked for me.)
To make things more complicated, there is also a kernel driver for your chip, bcm43xx.
So when knoppix boots up, that driver loads. It does not support WEP yet (as delivered on 5.0.1 but may by now in later versions). The bcm43xx driver also gave me an error msg about missing some firmware.

remove the kernel driver
rmmod bcm43xx

Install these 2 upgrades.
ndiswrapper-common_1.23-1_all.deb
ndiswrapper-utils-1.8_1.23-1_i386.deb
ndiswrapper -m
modprobe ndiswrapper

then
wlcardconfig and netcardconfig should set things up.

best,
john