From Hak5, here is a link to a USB “Switchblade,” which is basically a Windows-hacking USB key that is really slick. I’m looking into making this right now if I can find a spare key.
The show notes on this section are helpful as well. I only have one U3 key, so I have been playing with the non-U3 technique. You still have to click something when using a non-U3 key. I may look for a small, cheap U3 key here soon.
Even more info on the forums.