How to update firmware of my iPod Touch in Ubuntu?

As far as I know iTunes doesn't support Linux OS, though it is very strange. I need to update a firmware of my iPod Touch and don't know how to do that.

Could anybody help me to solve this problem please?

Update 1

I know that it is possible to install Windows in VirtualBox and use it right from the Ubuntu. But should I buy Windows (for some 100Euro) ONLY to update firmware of my iPod? Isn't it devil Apple, that makes us to buy things?

You could use a virtualization software like VirtualBox and install Windows. It's not possible using Wine, I don't think Wine would be able to gain access to the iPod as a "device".

If you're using VirtualBox, do remember to use the PUEL version, rather than the OSE version since the OSE version doesn't have USB support and cannot pass-through USB devices to the guest.