After you flash your 6720s with the hacked BIOS you might want to rebrand your Broadcom WiFi card so it gets detected as a genuine Apple Airport Extreme card. The method is outlined by Prasys in his BLOG.
If you try this running a normal BIOS your card wont pass the whitelist check once is modified!
If you try this running a normal BIOS your card wont pass the whitelist check once is modified!