You'll need to install the b43-fwcutter package, and follow the instructions here, keeping in mind they might be a little out of date:http://www.linuxmint.com/wiki/index.php ... om_bcm43xx
That said, like the author, I found that the ndiswrapper (using the Windows drivers that came with the card) tends to work a bit better for me, but it's been a while since I had that particular card, and I'm guessing fwcutter has gotten much better. Try fwcutter first, and if that doesn't work, try ndiswrapper (removing the fwcutter stuff first).
Oh, and apt-get doesn't work so well with no network...lol...so download the .debs you need, and install with 'dpkg -i' instead (as administrator). Hope this helps a bit.