Detours alternative for Registry interception

The EasyHook Library might be what you are looking for. It is licensed under LGPL and its description sounds quite nice.
I have never actually used it myself because Detours was always enough for my private projects.

There is also an article about it on CodeProject but that is rather old and shows only .NET examples.

You can also use Deviare API Hook if you want to solve also the IPC or Deviare In-Process for a Detours replacement. It's open source and well maintained.