How to change Windows 8 Start Background Image and Color Scheme?

I want to change the style of the Windows 8 Start Screen:

Under Charmsbar > Settings > More PC Settings > Personalize > Start Screen you can choose out of 20 predefined background images and between 25 predefined color schemes:

How can you specify your own custom Windows 8 Start Background Image and Color Scheme? There were multiple Tools for the preview version like Windows 8 UI Tweaker or My WCP Start Screen Customizer, however none of them seem to work in the final release version of Windows 8.

Use ModernBack Changer:

It works with Windows 8 RTM and lets you change both the background and accent color.

There are no applications for the final release yet, the Accent settings are found under:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Accent

If you feel like hacking around...