broadcom bcm43xx chipset?
this laptop actually connect at all?
sorry to sound skeptical but broadcom has kicked me in the face more than once. i'm definitely NOT a fan.
you are right that the BT shipped driver has been patched for injection, but i still say you can't make chicken salad out of chicken shit. if it were me, i'd grab a good wifi card to use on the side.
sorry im not much help, just trying to save you some misery. (i own a d620 as well)....
as an aside, if you used ndiswrapper to get this card up, forget injection altogether.