(adsbygoogle = window.adsbygoogle || []).push({}); How do you unlock the passcode to a iPhone 3gs?

I want to unlock it so I can restore it on itunes then jailbreak it.

Since when did you need the passcode to do a restore? If you're going to restore it and it does need a passcode, just enter DFU mode and Shift+Click 'Restore' in iTunes, select the firmware and let it do it's thing.