A Festive update for you all, dear followers!
The Broadcom drivers are now working again in this special edition x86 generic build http://chromium.arnoldthebat.co.uk/special/Cx86OS_R33-5111_broadcom.7z
In order to get this to work, still follow the guidelines http://arnoldthebat.co.uk/wordpress/2013/02/24/how-to-get-the-broadcom-wireless-drivers-working/
If you intend on using this from harddrive, install to drive (usr/sbin/chromeos-install) before installing the drivers to USB drive since that appears to destabilise things a bit (dmesg shows hundreds of shill sessions dying).
If you want to run from USB for ever, feel free of course to install the drivers to that.
The dev server will reset the kernel however, so you will lose wireless functionality if you decide to use the dev server to update.