First of all, you should check the "official" topic about the issue, and just to clarify, we all tried to update that firmware...
If you wan't you could try it, there are tutorials online, and only thing worth mentioning is how to put it in dfu mode:
arduino.cc/forum/index.php/topic,53290.msg380874.html#msg380874
from there you just install drivers for the chip you have, then start flip, open USB, select device, load hex file from arduino hardware smthing, and burn it....
cheers, xvjeko