Today was released a method, how to read out Wii disks. Unfortunatly it takes about 50 hours, that's why some patience is required.
You need an LG-8164b or LG-8163b DVD-ROM drive, DVDInfo Pro (http://www.dvdinfopro.com) and an installed .NET framework.
The tool RAWDUMP.EXE makes, as the name says, a raw dump of the game and the tool UNSCRAMBLER.EXE decrypts the image.
The required files should be found via Google.