Those settings are entirely in the registry. You could probably open the ADM/ADMX file to see specifically where in the registry, and you could certainly use PowerShell's registry drives (HKCU: and HKLM:) to modify the appropriate registry keys. I don't personally know where those settings are in the registry – you would need to research that. http://technet.microsoft.com/en-us/library/dd939844(v=ws.10).aspx would be a good place to start – I believe it lists the keys you are looking for.
When you modify a setting that's under "Administrative Templates" in the group policy editor, it gets stored in a file called registry.pol in the GPO's folder. Assigning those settings directly in the registry has a similar effect as far as the system's behavior is concerned, but you won't see the changes in the Group Policy console.