Well, you could make a shortcut to explorer on the desktop, for example. And then you can add a command line switch to the shortcut. Something like this, explorer /root,C:\program files will open the explorer window in Program Files.
This may be an alternative to what you are trying to do.
Also, you can just make a shortcut to the folder you are trying to set as default if this person needs access to a certain folder a lot. The explorer command line and the shortcut to the folder do basically the same thing.