Anyone doing this?

You have to be careful to avoid loaded HKU DefualtUser-Hive "hanging" on the Machine. If c:\users\default\ntuser.dat remains opened logon will fail.

My favorite Solution would incorparate a .reg File and the regedit /s command. It simplifies changes. But I receive this Error with every text file Action (ZCM 11.1):

An error occured while performing the "Edit Text File Action" action. The error message is - "{1}".
(the reg-file has to be Ascii: UGTS #36: Registry .reg files and Unicode

This Error happens when the file already exists.

since i have to use "reg load" anyway i do it with a cmd script now:

reg load HKU\dflt "C:\Users\Default\ntuser.dat"
timeout /T 1 /NOBREAK
reg add "HKU\dflt\Softw..." /f
reg add ...
timeout /T 1 /NOBREAK
reg unload HKU\dflt

The "reg unload" does not complete if the "reg add" has not finished completely! This is the reason for the TIMEOUT command.