Follow these instructions if you are using the b43 driver from linux-2.6.25 or compat-wireless-2.6, or from any current GIT tree.
Softwares/Drivers:
b43-fwcutter version 011: available in latest Linux distributions.
Broadcom’s proprietary driver version 4.150.10.5: download at: http://mirror2.openwrt.org/sources/broadcom-wl-4.150.10.5.tar.bz2
Usage:
tar xjf broadcom-wl-4.150.10.5.tar.bz2
cd broadcom-wl-4.150.10.5/driver
b43-fwcutter -w /lib/firmware wl_apsta_mimo.o
Note that you must adjust the FIRMWARE_INSTALL_DIR path to your distribution. The standard place where firmware is installed to is /lib/firmware. However some distributions put firmware in a different place.