This was my original answer:
Log in as the restricted user, then go to c:\windows and right click
on regedit and click "Run as Administrator" (you will be asked for the
credentials), and make the same registry changes.
OK, to be honest, after I wrote the answer, I decided to test it, and double-check my answer as I often do. What I found blew up a long-held thought that I had, and I am going to mention it now because I am sure that I am not the only one, who will be surprised.
Despite being logged in as my user "Test", when I ran regedit.exe as administrator (or even a second administrative user), instead of it ONLY running the program with elevated privileges, it also changes the HKEY_Current_User hive to that same administrator account. I was extremely surprised.
So I would do it this way for simplicity: Elevate the user to administrative level temporarily in Control Panel>Users. Log in as that user, and make the registry change exactly as you had above. You can test it immediately by right-clicking the taskbar. Log out, and back in as administrator, and demote the user back to standard. I tested this and it worked.
An even easier way: While logged in as your administrative user, elevate the standard user to administrative level temporarily in Control Panel>Users, then follow the original answer. Now running regedit as that user, it will load their hive, and you can edit it. Then demote them again. This way, it is all done without logging in and out.
I think this is clear, but if I did make something a bit confusing, just ask in the comments, and I will try to clarify.