How to set default screensaver, but leave selection open?

I'm working on a group policy to enable a screensaver and lock it out after 10 minutes.  So far I have these four items:

1.  HKCU\Control  Panel\Desktop\ScreenSaveTimeOut  |  Action:  Create  |  Value type:  REG_SZ  |  Value data:  600

2.  HKCU\Software\Policies\Microsoft\Windows\Control Panel\Desktop\ScreenSaveTimeOut  |  Action:  Create  |  Value type:  REG_SZ  |  Value data:  600

3.  User Configuration\Policies\Administrative Templates\Control Panel\Personalization\Enable screen saver  |  Enabled

4.   User Configuration\Policies\Administrative Templates\Control Panel\Personalization\Password protect the screen saver  |  Enabled

Those all work, in the screensaver box, it's set to 10 minutes and On resume, display logon screen is checked and both are grayed out.  The problem is I need to set a screensaver for it to work, right?  I've figured out how to load a screensaver, but the method I've used locks that option so users are unable to select their own screensaver.

Is there a method to load a default screensaver without graying out that option for users?

Thanks