OK, so presumably, when you insert this USB drive into your computer some kind of program (the one that is asking for a password) is already being run automatically. When this program starts up it is probably creating some kind of focus event in VoxCommando. Depending on the name of the program that is running, assuming it is unique, you can use this to then send the password using keyboard emulation. There is already a lot of information available on keyboard emulation and events so I won't go into the details.