How can I write a virtual BT device?

Hi all.

Is it possible to write a local application that simulates a virtual BT
device (i.e. GPS, hands free, ecc.)?

I basically want to run such application on my PC and then run "hcitool
scan" on the same PC and discover also the virtual device exposed by the
application.

If this is feasible, can you please point me to the main component of BlueZ
I should look at?

Thanks in advance.
Massimo