How to jailbreak 2nd gen iPod Touch without losing data? I have an 8GB iPod Touch 2nd Generation that runs iOS 4.2.1, and currently it is not jailbroken.

I want to jailbreak it using redsn0w version 0.9.6b4. I have found these instructions, but I will lose data if I follow them. I have backed my data up using iTunes. How can I jailbreak it without losing my data? Or can I restore the backed up data without removing the jailbreak?
I've used redsn0w on iPod touch 2nd Gen. You will not lose any data.