Ipod 3rd gen, iOS 4.2.1 to iOS 5.0.1?

Requirements:

Point your hosts file to cydias servers instead of apple servers. (need to have the shsh on cydia for the version you are upgrading to for it to work)

If you ahve that, then download 5.0.1 from online somewhere.

Take the ipsw, and change the file extension from .ipsw to .zip or .rar

Use winrar to take out the .plist files

Change the info in the plist files from 5.01 to 5.1 (need to change the version and the code for that version, like 5.0.1 is maybe A1C for example, i forgot what it was, so dont use that one)

Then after editing them, save them and put them back into the zip/rar and replace the old ones.

change it back it .ipsw

Then do a shift-restore from dfu mode, and it should work.

Its been a real long time since ive done this, but it has worked to do from 3.1.2 > 3.1.2 (when 3.1.3 was the newest and 3.1.2 was no longer supported) and 3.1.2 > 4.3.3 (when there was 3.4.5 released and 4.3.3 was no longer supported). i updated to 5.0.1 when it was the current version when there was an untethered JB.

Also unreleated, but http://www.i-funbox.com/ is an awesome jailbroken application to have. Same thing as like winscp, but uses your usb instead of wifi (as transfer through usb is 10-20MB/s, where was wifi couldnt possible hope to get close).

It can be used for backup even on non JB devices, to back up music, videos, images, apps,etc