I would suggest using the gui drakconnect that you had started with, instead of trying to use slack instructions. If “ndiswrapper -l†doesn't show any device, it's not working. You must find another bcmwl5 driver to try to use. There are many available on the net to d/l and try.
Alternatively, you could use Broadcom's IEEE 802.11a/b/g/n hybrid Linux® device driver. It's here: broadcom.com/support
It will require a bit of work on your part to use, but the instructions are there.