THe 64-bit Broadcom drivers can be found here
It's the one at the very top of the list.
Ndiswrapper DOES work under x86_64, (it's worked for me under SuSE and Gentoo, so I'm assuming it'll also work under Fedora -- which I'll find out in about 3 hours). To install the driver you just have to cd into the directory where the unzipped drivers are, and enter ndiswrapper -i <inf file>
and it'll install the driver,
gives you a list of installed drivers and tells you if the hardware is present
Afterthat you just have to modprobe ndiswrapper
and (if you become your IP through dhcp) dhcpcd wlan0
and that should do the trick.
NOTE: If you want to connect to a VPN, I'Ve heard that ndiswrapper and the cisco vpnclient don't get along to well, other than that I haven't experienced any Problems.
Hope this helps