A program I have seen called Advanced Registry Tracer may do some of what your require or at least offer a good substitute. It wont lock the registry to my knowlage but it will allow you to easyly undo unapproved changes.

Here are a few of the features that may intrest you:
Compare different copies of the Registry
Compare individual branches of different copies of the Registry
Undo and Redo Registry changes based on comparison results: directly from the program or by generating the REG-files
Export / import any key of the Registry into / from the old REG file format (regedit 4) and from the new one (regedit 5)
Their web site is at http://www.elcomsoft.com/art.html