If you issue the command
Code:
cat /boot/config-3.2.4 | grep B43
you will get the lines
# CONFIG_B43 is not set
# CONFIG_B43LEGACY is not set
The Knoppix kernel does not support your BCM4312 wireless adaptor. There is no kernel module. Therefore downloading the firmware files and copying them to the proper place in the filesystem as described on the web page you mentioned won't help.

If you read the page "b43 and b43legacy" of the Linux Wireless web site you will find out that there exists a proprietary driver "broadcom-wl" you could try out. Don't forget to read the file README.txt on the Broadcom web page.

I hope that helps.