How to change region & system menu
Guide to Changing your Wii's Region and System Menu
WiFi Internet Access on your Wii or a game disc with an update for the target (desired) region
Zelda: Twilight Princess or other means of running homebrew applications.
Install the Homebrew Channel. You can find instructions on how to do this and the files to do so here: Setting up your Wii for Homebrew - WiiBrew
You could also do this directly with the Twilight Hack.
Download Waninkoko's Wii Custom IOS 37 rev 03 or higher (wii.waninkoko.info). Create a folder called "apps" on your Homebrew Channel SD card and create another folder inside that and call it "cios". Copy the "cIOS37_rev3-Installer.dol" file into this "cios" folder (\apps\cios\) on your Homebrew Channel SD card. Rename the "cIOS37_rev3-Installer.dol" file to "boot.dol". Download the "IOS37-64-v2070.wad" file from somewhere. (Google.de for it). Put the "IOS37-64-v2070.wad" into the root (main folder) of the SD card.
Download Waninkoko's Wii Region Changer from his site (wii.waninkoko.info). Extract the Region changer's files. Create a folder in the apps folder on the Homebrew SD card called "regionchanger" and move the "Wii-Region-Changer_v1.dol" file that you extracted into that folder. Rename the "Wii-Region-Changer_v1.dol" file to "boot.dol".
Download Waninkoko's Wii Custom IOS Downgrader from his site (wii.waninkoko.info). Extract the Custom IOS downgrader's files. Create a folder in the apps folder on the Homebrew SD card called "cios_downgrader" and move the "cIOS_Downgrader_v1.1.dol" file that you extracted into that folder. Rename the "cIOS_Downgrader_v1.1.dol" file to "boot.dol".
If you have a modchip set its region to the target region (i.e. the region you want to change to) In my case this would mean setting it to NTSC-U (North America).
For WiiKey users this means downloading the WiiKey update 1.9s disc and WiiKey 1.9s config disc from wiikey.cn/resources for the target region. Again, in my case this would mean downloading the NTSC-U (North America) version of the update and config discs. Burn both discs using ImgBurn or Nero (etc.).
You're now prepared to start the main opeation.
If you havent already set the region for your modchip, do so NOW.
For WiiKey users this means running the update disc and completing the update. Ignore any warnings about using the correct region. From this point onwards you wont be able to read any game discs anymore until you're done with the region change operation. Dont run the config disc yet.
Start the Homebrew Channel. Find the Custom IOS 37 rev 03 installer item and run it. Complete the installation and it will reboot. You now have the Custom IOS required to do the operation.
Start the Homebrew Channel. Find the Region changer item and run it. Select your desired (target) region by using the left-right buttons on the D-pad. In my case this would mean hitting right till I see NTSC-U (North America). Push the A button. This completes almost immediately so dont be surprised. At this point your Wii's region is now changed. It will reboot. After reboot your warning screen should have changed and the system menu will show up fine. The settings menu will not work yet. This will be fixed in the next step.
Start the Homebrew Channel. At this point you need to have WiFi connectivity (through wireless router or Nintendo WiFi USB stick, etc). Find the Custom IOS Downgrader item and run it. You will get a list of the existing firmwares that you can install. You can scroll down to see the rest of the list by using the up-down buttons on the D-pad. Select the firmware you like and press A. In my example, since my Wii had firmware 3.1J before the change, I decided to keep it at 3.1 and so I selected 3.1U. Make sure you pick the firmware that corresponds with your new (target) region. 3.1U is for NTSC-U (North America), 3.1J is for NTSC-J (Japan), and 3.1E is for the PAL region ( 3.2 is now the recommended version ). Once you press the A button it will install the necessary files (this could take a few minutes depending on your connection speed, but you will see the progress) and will the reboot.
Alternatively, if you dont have a WiFi connection, you can use an orignal game disc with an update on it for the target (new) region and let it do the update.
If your modchip has a configuration disc run it. You WILL NOT be able to play any games or read any discs until you run the config disc and save the settings.
For WiiKey users this means running the config disc that you burned earlier and choosing configure and choosing the settings you like there
Go to the settings menu and select the Language of your preference. Make sure you do this step, otherwise you might have some leftover text using the old language. For example on Japanese Wii's if you dont go the Language menu and select English, you might have leftover Japanse writing in the Photo Channel, etc.
Congratulations, If you followed the steps correctly you should now have a Wii with the region of your liking. I know a lot of NTSC-J (Japan) Wii owners will be really happy, like I was.
Thanks for making this possible Team Twiizers, bushing, marcan and of course Waninkoko and AlexDP for bringing it all together
NOTE: I hold no liability whatsoever for anything going wrong with your region change operation, whether you followed the directions or not. I do not take any responsiblity for any damage to your Wii console, hardware, software, etc.
If you follow the directions correctly though you shouldnt have any problems.