You could try firmware-openfwwf.tcz is it in optional folder or onboot.lst ? Not sure which build your using. The only other option is use b43-firmware-cutter.
The following may assist Broadcom 43 owners: Broadcom BCM4323 050d:615a Belkin N600 USB 2.0 802.11 a/b/g/n 2.4GHz/5GHz WPA/WPA2 Requirements 3.0.21-tinycore wifi.tcz ndiswrapper.tcz More Information http://forum.tinycorelinux.net/index.php/topic,12910.msg73169.html#msg73169 Broadcom Corporation BCM4312 14e4:4315 Dell Latitude D430 rev 01 mini-PCI 1395 802.11b/g 2.4GHz/5.0GHz WPA\WPA2 Requirements 3.0.21-tinycore See link for more info on obtaining driver and firmware http://forum.tinycorelinux.net/index.php/topic,12910.msg71013.html#msg71013 Broadcom Corporation BCM4331 14e4:4331 Apple Inc. Macmini 5,3 rev 02 PCI802.11a/b/g/n 2.4GHz/5.0GHz WPA\WPA2 Requirements 3.0.21-tinycore64 compat-wireless-3.2.5-1 +user supplied firmware Various solutions available for this adapter See link for more info on obtaining driver and firmware http://forum.tinycorelinux.net/index.php/topic,12910.msg71023.html#msg71023