How can i downgrade my ipod without downloading any software?

i want to downgrade my 4.1 ipod to 4.0. i want to do it without any software or downloading or any of tht bullcrap! first because im not allowed too and 2.. im afraid of viruses,, is there anywaye to downgrade ipod 3g 4.1 to 4.0 without any software or downloading?