This here is betwiin, a NAND flash conversion tool for Wii NAND images. It can re-encrypt and re-HMAC the per-console unique parts of a NAND dump from one Wii such that it will run on a second one.

• Copy input dump file to input/flash.bin.
• Copy input keys to input/.
• Copy output keys to output/.
• Run betwiin.py, wait several minutes.
• Take output file from output/flash.bin and use as appropriate.

• The version of boot1 you flash to a NAND chip must match the original one that shipped with that Wii. No exceptions.
•  The version of boot2 must be equal to or greater than the one most recently installed on that Wii.
• No handling of bad blocks is performed; if your target NAND chip has a bad block that hits an important file required for system startup, I suggest you find a differente donor dump to start from.
• Converting an image from one keyset to another does not guarantee everything will work. The serial number will be cloned, but that should not affect anything. The Wii Shop account will not transfer over, nor will the original account used on the broken Wii work. Most savegames should still work. Purchased channels will not work on the new Wii, nor will you be able to redownload them. You should be able to create a new Wii Shop account, all disc-based games should work, you can update the system online, etc.

• Wii homebrew - Homebrew Browser v0.3.4
• Wii homebrew - Revolution Engine v0.4 alpha 2
  

Via Wiibrew