Couple points.

1. If you're going to type in the UBB Code Tags they need to be in lower case not UPPER CASE to work.

2. What version of KiXtart are you using?

3. What is you're current issue? Your code to add the Key works fine. Do you want to know how to add the other keys and values with KiXtart or how to shell to regedit and import them?

Code:
Dim $Key
Break On
$Key = AddKey("HKLM\Software\Policies\Microsoft\Windows\WindowsUpdate\AU")
If $Key = 0
  ? 'SUS registry key added!'
Else
  ? 'SUS Key was not added. ' + @SERROR
Endif


When I look the key is there.