Can you elaborate on what your problem is, as I don't understand your question. The kixtart script is identical whether it's run from the netlogon folder using the user profile tab in active directory or when its run from the gpo. The only difference being is that you have to use the logon section if you don't want to change your kixtart script as the startup section in the gpo won't run anything in the user context.

Are you asking how to run kixtart scripts in the startup, shutdown, logon and logoff sections within the gpo or are you asking something different. GPO scripts don't run from UNCS. You need to copy your script to the location of the gpo and then tell it to run kix32 and specify the name of the kixtart.kix file in the optional parameters.