I believe you can. you would load hci_usb (if it isn't automatic)
the advantage of using usb is you can use an off-the-shelf part and you can use an EDR adapter at the full 3Mb. and, of course, you can use it for audio which I think the internal bt can't do still.
I don't have a verdex to try but I believe even a bluegiga could be connected over usb with a regulator thrown in... see http://bluetooth-alsa.sourceforge.net/embed.html
btw, lots going on in the next few kernel revs:
* a patch was just accepted to regulate the packet flow for sco will bring headset audio quality up to the minimum standard
* the main limitation of using usb instead of a uart is being worked on now on bluez-devel: allowing multiple simultaneous headset (sco) connections.
* we also have some patches floating around for using esco for better quality.