1) That howto is for bt4b which uses kernel 18.104.22.168 iirc.. bt4pf now uses kernel 22.214.171.124
2) Broadcom deliberately removed rfmon functionality out of their sta driver but the same case was not applied in window's ndis driver. More information can be found here
3) Its pointless using wl at any rate.. if the broadcom-sta package fails to work you may as well try to replace the minipcie card for a supported one. (Compaq, HP, Lenovo, IBM laptop owners beware that this does not in your cases because your laptop has minipci/minipcie wireless card whitelisting which means that only a handful of wireless cards on the list are supported)
At any rate, I'd sell either the broadcrap card or sell the whole laptop. Not worth pouring in any amounts of effort flying broadcrap flag.