http://forums.ih8sn0w.com/viewtopic.php?f=13&t=408

I just done this with my 64gb iPod Touch 3G mc model. I got to step 3 though and it downgraded my firmware so there was no need for step 4, for me anyway.

Hope it helps people here.

Quote:
Materials

- Iphone 3GS or iTouch 3G (MC model) with 3.1.3 firmware
- iTunes 9.0.3.15
- Libusb => here (http://sourceforge.net/projects/libu...2.exe/download)
WARNING : Do not install Libusb on a 64 bits system …(it is a 32 bits application, if you do so, your PC will crash)
- iRecovery by fongn => here (http://www.megaupload.com/?d=VMZMYHWV)
- firmware 3.1.2 => here (any device) (http://www.felixbruns.de/iPod/firmware/)

Step 1

Download 3.1.2 firmware for your device on your PC (if not already done) and check your iTunes version.

Step 2

a) go in C:\Windows\System32\drivers\etc (for Mac, go in /etc/hosts.).
b) Put the Hosts file on your desktop (or anywhere else than system32)
c) Open Hosts with BlocNotes (you must have administrator rights)
d) At the end of the document add the two following lines
74.208.105.171 gs.apple.com
74.208.10.249 gs.apple.com
e) Save the file, put it back where you took it : C:\Windows\System32\drivers\etc
f) Reboot your PC

Step 3

a) Open iTunes, plug your device and wait the end of synchronization.
b) Put your device in DFU mode
c) Press SHIFT on your keyboard while clicking on Restaure in iTunes. Search for your firmware you already download.
d) This step is critical … At the end of the restauration, you must have the following error : 1015. If you get it, click OK and close iTunes.

IF YOU GET THE FOLLOWING MESSAGE WHILE RESTORING YOU CAN’T downgrade for the moment … sorry about that …
This device isn't eligible for the request build
e) Your device must now show iTunes logo and USB port (recovery mode)

Step 4
a) Unpack on your desk Libusb-win32 and choose Execute
Then, click ok to go through all steps and a window should open showing lot of things. Let it open
b) Open iRecovery, wait for the recovery and run menu 2 “Reparer le boot” (Repair boot) and it’s done !
c) Reboot you device (HOME POWER for 10 seconds.
The iPhone is normaly down. But in any case unplug it from usb port.
Turn on your iPhone or do what you have to do to keep your contacts, sms, setting, etc.
d) Set it up as a new iPhone or take a save if you don’t want to lose your contacts, sms, settings, etc.
Your device is back in 3.1.2 and you can jb it back …

Thanks to GenoX, diki16, Timinet and Ptipois from iPhone.fr

Results are surprising … success is random.