I've ported Sam Phung's CE registry editor, as on Codeplex to Compact 2013. Source code is there as well as binaries. http://regedit4ce.codeplex.com
The source contains VS2008 and VS2012 project files so it can be seamlessly used to build for Windows Embedded Compact 7 or. Compact 2013 (Compact Framework 3.5 or 3.9).
As its Managed Code (C#) with no PInvokes it works on ARM and x86.
It will be included in next release of Compact13Tools (V3,0) coming soon.