Windows 7 Taskbar Custom Preview

I am using the Windows API Code Pack and trying to define a custom preview image when a user hovers over the appication icon on a Windows 7 taskbar.

I can can get it to show a thumbnail of the app window (or a cropped region of the window), but what I would like to achive is show a thumbnail of an image that isn't displayed in the form itself e.g. My.Resources.SomeImage

Any help would be appreciated.

Thanks

Stuart