PwnageTool has been updated by msft.guy to jailbreak iPhone 3GS on iOS 4.2(Old bootrom only). PwnageTool does hacktivation but is currently incompatible with Cydia. You’ll have to use OpenSSH to manually install Cydia applications.
Here is the step by step guide:
- Download PwnageTool 4.01: http://rapidshare.com/files/401909987/PwnageTool_4.01.dmg
- Download iPhone 3GS 4.2 bundle here and extract it on your desktop.
- Download iOS 4.2 for iPhone 3GS. If you are an official developer, then you can download it via Apple. Else google it.
- Right click on the PwnageTool file downloaded in step 1 and click “Show Package Contents”.
- Navigate to Contents/Resources/FirmwareBundles/ and paste iPhone2,1_4.2_8C5091e.bundle file in this location. Close the folder now.
- Now start your PwnageTool and browse for iOS 4.2 ipsw file.
- Click on “No” when PwnageTool asks you “Do you have an iPhone contract that would activate normally through iTunes”?
- PwnageTool will now create a custom ipsw file for your iPhone 3GS.
- Restore this custom ipsw on your iPhone 3GS by pressing shift/option key and click Restore. Give the path to custom ipsw created by PwnageTool.
- Now sit back and relax. iTunes will restore your iPhone to 4.2. It may take some time.
Congrats. You now have iPhone 3GS jailbroken running iOS 4.2