We were asked many times how to put the iPhone into DFU mode without pressing the Power Home or damaged home button, especially with iPhone3G, 3GS. Earlier it wasn’t possible but today iPhone Dev Team has implemented a new option in Redsn0w to put the device into DFU without using the buttons.
This feature creates a custom firmware, so when you restore your device will boot in to DFU mode. Just connect your iPhone, select your firmware and click the “DFU IPSW” and Redsn0w will be create a firmware to restore your iPhone in DFU, jailbreak or whatever you need.
Download Redsn0w :