1 / Uninstall iTunes 8.2 .
2 / Install iTunes 8.1.1
3 / Place your iPhone (under 3.1 or blocked restores) in DFU
4 / Make a left Shift + Click Restore and select your ipsw 3.0
5 / Once the restoration is completed you'll get an error 1015 (Do not worry this is normal)
6 / Do again a restore but this time not in DFU mode but in the rescue Mode ((Displaying the USB cable on the screen) After the error 1015 phone goes into rescue)
7 / Once this second restoration always an error 1015
8 / Close iTunes (8.1.11)
9 / Open Quickpwn 3.0 (unofficial)
10 / Quickpwn will tell you that you must reset your device, to do so, 15 seconds remain supported on Home + Power. Your phone turns off, release all, press 2 sec on power and now the iphone tell you that only one emergency call is allowed
11 / Now itunes will say that the iphone can only be used with version 8.2 of itunes.
12 / Uninstall 8.1.11 and install itunes 8.2
13 / Use Redsn0w for jailbreak your phone you're done
PS: The modem is always on 05.08.01, so the network must wait for an Yellowsn0w update