First we need to be sure, that u r running Lion 10.7.
Assuming, u already have hidden 'Recovery HD' partition (if not, then google for instructions)
Now, open terminal and type (w/o quotes): 'defaults write com.apple.DiskUtility DUDebugMenuEnabled 1'
This will enable Debug menu in Disk Utility. Open Debug menu and check 'Show every partition'.
U will see in Disk Utility all hidden partitions r gray. Select 'Recovery HD' partition and click Mount.
Browse to the 'Recovery HD/com.apple.recovery.boot/BaseSystem.dmg' and mount it.
Now, in this image browse to the 'BaseSystem/System/Installation/CDIS/Lock.app'
But, u cant lock nothing with it actually... I also dont know what code is to be used. I dont have iCloud.
Maybe this will give someone an idea...
Credits goes to the mac geeks, I just accidentaly found Lock.app, when I was looking how to put some useful utilities on that partition. I put DiskWarrior.app into Utilities folder, but it wont show up on boot. (It is defenitely there on the image. Checked with Terminal ls command.)
If any one have an idea how to get some more from Recovery HD partition, would be very glad.