Use command-line options to edit registries with regedit exe

reg restore HKLM\Software\Microsoft\Test RegBackup.hiv. This command will restore the contents of the RegBackup.hiv file into the Test key.

reg save	Exports specified registry subkeys, entries and values into a named file. Examples of use: reg save HKLM\Software\Test\AppTest BackupFile.hiv. The command saves the AppTest hive to the BackupFile.hiv file.
reg unload	Removes the registry section loaded by the reg load operation. Example of use: reg unload HKLM\TestHive. The command unloads HKLM\TestHive from the registry.