That guide is directed toward Broadcom's proprietary STA driver (also known as the 'wl' driver because that's what the kernel module is called). It looks like your chip is not supported by that driver, but instead needs the open source b43 driver.
Details are on this page:http://linuxwireless.org/en/users/Drivers/b43
All you should need to do is install firmware-b43-installer (you can install it using Synaptic). Then, you can either reboot, or load the b43 module using modprobe.
One more thing, you'll either need to install one of the AV Linux testing kernels, or force the wireless card into PIO only mode. This from the b43 driver page linked above:
BCM4321: some cards do not work in DMA mode with kernel 3.1 and older. Problem was fixed in 3.2. A workaround for older kernel is to use PIO mode (b43.pio=1 module param).
If you have any more questions, feel free to ask. Good luck!