How big of a difference is there between an Arduino Uno and the rest? Lately I've been fooling around with a project for my Microsoft Sidewinder Force Feedback Pro Joystick. I've found out that there is a project currently for it built for the Teensy 2.0. On the page for the Teensy 2.0 there is a link for an Arduino Library for the very same project that was (I guess) converted. There isn't much documentation for it, and I don't think there is much progress being made on it anymore. However when I grab the files and try to upload it to my Arduino Uno it spits out an Unsupported device. Doing some digging around I found where it shows what devices are supported in the includes.h.. Which happen to be

#if defined(__AVR_AT90USB162__) || defined(__AVR_AT90USB82__)
 #define __AVR_AT90USBX2__
#elif defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)
 #define __AVR_ATmegaXU4__
#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__)
 #define __AVR_AT90USBX6__
#else
 #error "Unsupported device"
#endif


Which ends up being the red arduino, arduino micro, arduino leonardo, and I think a few teensys. 

What I want to know is if you can upload this code onto a UNO. I'm not really wanting to purchase a teensy just to check if this will work or not.
That program will make the arduino board act like a keyboard to the PC it's plugged in. This can't be done on the Uno, since it doesn't have USB support.