When iOS 4 jailbreak first came out, it was only compatible with iPhone 3GS, iPhone 3G and iPod touch 2G.Things were even more trickier for iPhone 3GS.
If your iPhone 3GS was not previously jailbroken with anything other than Spirit, iTunes used to throw an error whenever you tried to restore your phone with custom firmware. Sn0wbreeze 1.6.2 later brought support for these Spirit’ed devices. But in case if you are still getting problems restoring to custom cooked iOS 4 firmware (from PwnageTool or Sn0wbreeze), you can use Spirit2Pwn patch to perfectly restore your iPhone 3GS on iOS 4 custom firmware.
Steps are given below:
Step 1: Start Cydia on your iPhone 3GS (old bootrom, jailbroken on 3.1.3 using Spirit) and touch on “Manage” tab on the bottom. Now touch on “Sources” as seen in the screenshot below.
Step 2: Touch on “Edit” and then on “Add”. You will be prompted to enter a url source as seen in the screenshot below. Type “http://repo.woowiz.net” and touch on “Add Source”.
Cydia will now automatically update your sources by following a series of automated steps.
Step 3: Once the repository has been added successfully, Search for “Spirit2Pwn” in Cydia and install this application.
Step 4: Now from here onwards, simply follow our previous guides on how to jailbreak iOS 4 on iPhone 3GS using PwnageTool 4.0 / 4.0.1 for Mac, and Sn0wbreeze 1.6 for 4.0 on Windows guide.
Once you have jailbroken your phone, you can unlock it using ultrasn0w 0.93 (on any baseband).
You could always get support from UnlockAlliPhone.com about any Unlock & JailBreak issue of any model of iPhone including iPhone 2G,3G & 3GS and also upcoming iPhone 4. They provide Premium Members Support for life time. Means just pay one time a small fee and you will receive support(real human support – avg response time 2 hour) for all present & future version of iPhone.