Using iFile to change lock screen passcode
It should be, is for sure in iOS6 and will ever be encrypted in future iOS versions. I doubt you can bypass the code.

However there is a securityleak in iOS 5 (since you have 5.0.1) I think you should check out this post online

The post contains this video, on how to bypass the lock. I hope that will help you out rather than changing the code via iFile.