When you plug the internet stick into a Windows based operating system, a virtual cd-rom is created. Once the software is installed, inserting the device runs the autorun.exe.
Obviously linux can’t use the system libraries in order to perform the same action, so what you will need to do is eject the cd-rom in linux.
The easiest way in backtrack 4 is to pop open the Konqurer->Storage Devices, hit refresh and you’ll see the cd-rom. Right click and eject.
Now, if you head to your console and type lsusb you will note that you have the correct drivers loaded, and /dev/ttyUSB0 will be available for your choosen modem dialer to use!