Windows – How to change Windows 7 Wallpaper using the registry

All I'm trying to do is get Windows to switch to a different Wallpaper folder at night (a folder containing night images). To achieve this I'm planning to use Task Scheduler to run .bat files which simply switch the names of the two folders around. That's pretty straight-forward.

The only problem is that Windows won't let me rename the folder containing the current Wallpaper image. This means I have to temporarily change the current wallpaper image to something else while I'm renaming the folders.

And to do this I need some kind of file to modify the registry key:
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Desktop\General\Wallpaper

I did find a script someone had written which I think does this, but it's too technical for me to understand. I don't know anything about the C language, what classes and namespaces are, or how to create a file that runs this code in Windows. Also, it seems like a lot of code just to change the value of a single registry key. And would I have to install software?

Perhaps someone could give me some help?

Also, could anyone confirm that the Windows wallpaper folder is not kept in the registry? If it was, I could simply change this, and wouldn't have to rename folders. But I've done a lot of searching and can't find any trace of it in the registry.