Enable USB 2.0
The Nintendo Wii for a long time did not support USB2.0 officially. While it has USB2.0 compatible ports, it actually only uses them at USB1.1 speeds (40 times slower).
After a while, USB2.0 was made available for certain apps (like Backup Loaders) by enabling it in the cIOS. But for apps that don't use a cIOS, this meant they could still not use USB2.0 speeds.
Finally, with the 4.3 update, an official IOS (IOS58) added support for USB2.0 speeds. If IOS58 is installed, homebrew apps (that don't use cIOS) will thus be able to use USB2.0.
This does not apply to WiiU since it always has IOS58 installed.
Note to 4.3 users:
Since IOS58 was introduced with the 4.3 update, it is available to all Wiis with that version. As such, the steps to install IOS58 do not apply to those systems.
However, if your Homebrew Channel is running on another IOS than IOS58 (you can check this in the menu on the top right), you will need to re-install it.
This only happens if you already had the Homebrew Channel installed and then updated to 4.3.
Do NOT attempt to do these steps on the WiiU! It may brick your Virtual Wii Mode!
Wiis below System Menu 4.3
An SD card
Homebrew Channel installed.
Method 1: IOS58 Installer (requires WiFi)
This method uses the IOS58 installer by Tantric. It requires you to have a WiFi connection on your Wii.
2. Insert the SD card in the Wii. Go to the Homebrew Channel and launch the IOS58 Installer.
Method 2: Manually installing the WAD
This method manually installs the IOS in WAD form. We can download the IOS through NUS Downloader.
1. Grab NUS Downloader (if you don't have it) and start it up.
Use the Database and navigate to IOS -> IOS58 -> v6176.
On the bottom, click Pack WAD. Then click Start NUS Download.
2. Once it is done, go back to the NUS Directory (Extras -> Open NUSD Directory).
Open the titles folder, then go to 000000010000003A and then 6176.
You can find the IOS58-64-v6176.wad file in this folder. Copy it to SD:/wad.
3. If you don't have a WAD manager yet, download one and set it up on your SD card.
4. Insert the SD card in the Wii. Launch your WAD manager.
Depending on the WAD manager it may ask you to choose an IOS to use. You can choose any IOS here.
You can use IOS249 if you did the cIOS Installation steps, or IOS236 if you have it. But you can also choose another IOS, like IOS36 to do it.
If it asks anything else, like NAND emulation, leave that disabled.
5. Locate the IOS58 wad and install it. Once you are done, exit the WAD manager.
Re-installing the Homebrew Channel
After installing IOS58, you will need to make sure the Homebrew Channel uses it. This is done by re-installing it with the HackMii Installer.
TODO: expand to full guide