An unofficial PwnageTool version have been released to jailbreak iPhone 3GS iOS 4.0.2. If you have updated your device to iOS 4.0.2, thenJailbreak iPhone 3GS iOS 4.0.2 Firmware you could use this guide to jailbreak iPhone 3GS (Old Bootrom) on Mac OS X or you could downgrade to the old iOS 4/4.0.1 firmware using this guide and then jailbreak it

NOTE : Since this is an unofficial release of the PwnageTool, you should do this process at your own risk.

1. Download PwnageTool from http://www.megaupload.com/?d=63NSJXYL

2. Connect your iPhone 3GS to the computer and take a backup of it in iTunes so that you could restore back your settings later.

3. Launch PwnageTool.

4. Choose your iPhone 3GS with iOS 4.0.2 and go forward.

5. PwnageTool will detect the iOS 4.0.2 firmware. Move forward.

6. When PwnageTool ask you ” Do you have an iPhone contract that would activate normally through iTunes? “, click on “No” if you are not on an officially supported carrier. Click on “Yes” only if you are having an officially supported carrier on your phone like the AT&T. PwnageTool will now begin to create the IPSW file. When the process is completed, a ” ihaz Success! ” message will be shown.

7. Now open iTunes and select your iPhone 3GS in it.

8. In Windows, hold the Shift key and in Mac OS X, hold the option key and click on ” Restore “.

9. Browse to the iOS 4.0.2 .ipsw file that PwnageTool cooked earlier and let iTunes do the rest of the iPhone 3GS iOS 4.0.2 jailbreak process. After the process is finished, your phone will automatically reboot and it will be jailbroken on iOS 4.0.2. You could now unlock your iPhone 3GS on iOS 4.0.2 using the guide posted here.

NOTE : If Cydia shows a blank white icon, then add the repo ” http://apt.saurik.com/cydia-3.7 ” in Cydia to solve it.