Pretty sure you will have to write a kernel module. Have a look at this thread from today:
About Device Driver Programming And Socket Programming
And maybe you will find this interesting:
Writing a Simple USB Driver
I do remember getting slightly peeved about that last one since there is some crucial information absent from it* which you will realize after being frustrated by it (the nastiest kind of hole you can leave in a demo, I know!), but it does provide a nice clear acurate (IMO) perspective.
* even worse I can't remember what it was and am doing totally unrelated things right now, so don't have the headspace to figure it out...sorry
