Edit: this has been featured on an Italian blog (I don't know why but I don't care) here.
As much as I and fellow Mac users Would like to believe differently Mac OS X is actually quite easy to hack if you have machine access. In this Instructable we are going to boot into single user mode (�(alt)+s at startup) and delete a file that the computer checks for at startup that tells it that it has been setup. If you follow this Instructable word for word than no harm should befall the target computer. I do not yet know if this works on Lion because I do not yet have Lion.
PLEASE READ THIS WORD FOR WORD BEFORE DOING ANYTHING .