You need to put them in the correct location "C:\Windows\Globalization\MCT" and apply the registry settings. The one on My Digital Life is incorrect for build 7100 it may apply to older builds here is the correct entries for build 7100.
Note: that location is a hidden protected OS file
Code:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\InstalledThemes\MCT]
"%windir%\\Globalization\\MCT\\MCT-AU\\Theme\\AU.theme"=""
"%windir%\\Globalization\\MCT\\MCT-CA\\Theme\\CA.theme"=""
"%windir%\\Globalization\\MCT\\MCT-DE\\Theme\\DE.theme"=""
"%windir%\\Globalization\\MCT\\MCT-GB\\Theme\\GB.theme"=""
"%windir%\\Globalization\\MCT\\MCT-JP\\Theme\\JP.theme"=""
"%windir%\\Globalization\\MCT\\MCT-US\\Theme\\US.theme"=""
"%windir%\\Globalization\\MCT\\MCT-ZA\\Theme\\ZA.theme"=""
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Wallpapers\KnownFolders\0\Windows Wallpapers\MergeFolders]
"%windir%\\Globalization\\MCT\\MCT-AU\\Wallpaper"=""
"%windir%\\Globalization\\MCT\\MCT-CA\\Wallpaper"=""
"%windir%\\Globalization\\MCT\\MCT-DE\\Wallpaper"=""
"%windir%\\Globalization\\MCT\\MCT-GB\\Wallpaper"=""
"%windir%\\Globalization\\MCT\\MCT-JP\\Wallpaper"=""
"%windir%\\Globalization\\MCT\\MCT-US\\Wallpaper"=""
"%windir%\\Globalization\\MCT\\MCT-ZA\\Wallpaper"=""