Can i jailbreak my iphone 3g to ios5 firmware?

I want to Jailbreak my iphone 3g (not 3gs) to an ios 5 firmware but i don't know if thats possible. Can i do it by downloading the ios 5 firmware and then download redsnow? Please help

Added (1). Also if you know how i can please give me directions on how to do so

Not possible
4.2.1 is the last firmware the iphone 3 can get