Take a look at reply #1, it a picture. This will work with the SMD UNO also. I done it many times.
http://arduino.cc/forum/index.php?topic=56283.0connect Uno to your computer via the usb port
* Hold ATmega8U2 Reset to ground (wire 1)
* touch "Normal" Reset to ground (wire 2)
* Remove wire 1
cd arduino-0022/hardware/arduino/firmwares/arduino-usbserial/
sudo dfu-programmer at90usb82 erase
sudo dfu-programmer at90usb82 flash Arduino-usbserial-uno.hex
sudo dfu-programmer at90usb82 reset
unplug the Arduino board usb connector
plug it back in.
Run the Arduino ide