The way I used to do it was tedious and was quite complex, however with the v2.0 release of the wafel_setup_mlc plugin, region changing has become much simpler.

It is identical to just rebuilding the MLC, but this has region changing specific notes added.

This does not change the region of the Gamepad, however you can still use an out-of-region gamepad with Aroma, which can be loaded with a Stroopwafel plugin, so you don't need to worry about getting a gamepad from the region you are changing to.
It also does not change the vWii region. If you want to region change the vWii as well, use vWii Decaffeinator on Light Mode to region change. I think you also need to regenerate the setting.txt.

Following this guide will wipe the MLC. You should back up any saves you care about before following. Its possible to do it without wiping the MLC, you just skip the Erase MLC and Delete scfm.img steps, but you will have to remove the old titles with this wupclient (Right Click -> Save As).

Keep an OTP and SEEPROM backup. Nothing should go wrong, but it is better to have the most important backups and not need them vs. need them and not have them.

DO NOT UNINSTALL ISFSHAX AFTER ERASING THE MLC AND DELETING THE SCFM UNTIL YOU HAVE SUCCESSFULLY REBUILT THE MLC AND CONFIRMED EVERYTHING IS WORKING.
I AM NOT RESPONSIBLE IF YOU FAIL TO FOLLOW INSTRUCTIONS PROPERLY.
If you need support, you can join my server and ask in #help

What you need

• Install isfshax. This is a requirement. You cannot region change without it. (You can also use de_Fuse, but at that point you probably already know what you are doing.)
  
  • Stop at the "Booting" section.
• The release of the MLCRestorerDownloader for your OS.
• The latest release of the MLC setup plugin.
• The latest release of the Payloader plugin.
• The latest files for Aroma. (If you already have it, you do not need to recopy it)
  
  • Read and tick the 4 boxes -> Click on Download Payloads and Download Base Aroma

Downloading the MLC Titles

1. Extract the MLCRestorerDownloader you downloaded.
2. Copy the otp.bin into the extracted folder.
   
3. Open a command prompt / terminal.
4. cd into the directory with the MLCRestorerDownloader (ie. cd /Downloads/MLCRestorerDownloader).
5. Run the application (ie .\MLCRestorerDownloader.exe for Windows users).
   
6. Type in 1 the for MLC titles.
7. Type in the number for the region you want to change to (ie 2 for USA).
   
8. Wait for it to finish downloading. You can do part of the next section while you wait.

SD Setup

1. Copy the wafel_setup_mlc.ipx to sd:/wiiu/ios_plugins.
2. Copy the wafel_payloader.ipx to sd:/wiiu/ios_plugins.
   
3. Copy the two wiiu folders from the Aroma .zip files to the root of the SD.
4. Make a folder called wafel_install on the root of the SD and copy all 52 MLC titles here.
   

Region Changing

1. Boot the console.
   
   • If it does not automatically go into minute_minute, go install isfshax.
2. Navigate to Backup and Restore.
3. Select Erase MLC and then press EJECT to confirm.
   • If it tells you MLC Erase not allowed, go install isfshax.
4. Select Delete scfm.img and press EJECT to confirm.
   • If it gives you a warning about bricking the console, do not continue and install isfshax. It's not playing around.
5. Go back to the main menu and select Patch (sd) and boot IOS (slc).
6. Wait for the LED to start blinking blue, this means the setup has started. Wait for it to stop blinking, that is when the setup has finished.
7. Shut off the console and put the SD back into your PC.
8. Check the wafel_setup_mlc.log file on the root and make sure there were no errors (everything should have 00000000, except for SetInitialLaunch, which will have a 1).
9. If everything looks right, delete the wafel_setup_mlc.ipx file from sd:/wiiu/ios_plugins.
10. Boot the console again, select Patch (sd) and boot IOS (slc), and you should be greeted with initial setup. Success!

Manually fixing the sys_prod

You only need to do this section if Set Region to X returned error FFFBFFEE. If it returned a 0, then you can skip this section.

1. Download the sys_prod.zip attached to this post and extract the sys_prod.xml from it.
2. Open the sys_prod.xml in a text editor, and change the product_area, game_region to the target region.
   
   • Region values: JPN - 1. USA - 2. EUR - 4
3. Change the code_id, serial_id and model_number values to the ones found at the stickers on the bottom of the console:
   
   
4. Save the file, and then copy it to the root of the SD card.
5. Download the wafel_sysprod_copy and copy it to sd:/wiiu/ios_plugins.
6. Boot the console and do the Patch (sd) and boot IOS (slc) in minute.
7. Leave the console running for ~30 seconds, and then you can shut it off.
8. Do step 6 again, but this time it should actually boot up. You do not need to delete the plugin from the SD, as it will delete itself after it has been ran.

After Region Changing

You can keep isfshax installed, or you can uninstall it. I would keep it, so you can load Aroma on boot without needing to install PayloadLoader, or as some form of 'brick protection'.

You can region change the Gamepad with DRXutil, but no instructions will be given here. Use at your own risk!

Credits

@SDIO: isfshax setup guides, the wafel_setup_mlc plugin, help get the PoC to work, cleaning up my code, making the region fixer more sane...
@shinyquagsire23: de_Fuse, minute_minute, and stroopwafel
@GaryOderNichts: Also help me get the PoC working
@rw-r-r_0644: Finding isfshax and implementing it

 

[Beber666]

hmm just have one issue indeed. The Vwii doesn't seems to work. It show a red screen, and then crash and go back to Wii U menu with green ahlos colors... Any idea ?

 

[Beber666]

Edit: Desinstalling isfshax fixed the problem