Priiloader (based on the app Preloader) is an app that replaces the first part of the system menu that gets booted. Like this it is able to load before the actual Wii menu appears on the screen.
This gives it several advantages:
Brick protection. (Brick = unusable System menu)
Load apps at boot, by installing a file.
System menu hacks (although this has nothing to do with the boot before the system menu)
WARNING! Do not install Priiloader on the Wii U! This will instantly brick the virtual Wii mode!
An SD card (Best results are with non-SDHC cards, SDHC will only work on 4.0 or above) formatted to FAT(32).
Latest Homebrew Channel installed
Will install priiloader.
1. Download the Priiloader pack and extract the apps folder to the root of your SD card. Merge with the existing apps folder if needed.
2. Run the priiloader installer with the HBC.
On the new screen press +. This will install Priiloader on your system.
If you get any errors about loader.ini or password.txt, ignore those.
It should now reboot in the Priiloader menu. If it doesn't, power off the Wii, then power it back on and hold reset while it's booting until you see it.
3. The Priiloader menu is white by default, you can change it to black in the settings if you prefer. If you want, you can install some system menu hacks now (by going to System Menu hacks).
Installing a file
One of the special functions of Priiloader is that it can autoboot any file instead of the system menu.
So here's how to do it:
1. Make sure that the dol you wish to autoboot is on the SD card. Priiloader should detect the same .dol files as the homebrew channel (aka every boot.dol in the subfolders of /apps/)
2. Run Priiloader (by holding the RESET button while the Wii boots.)
3. Now go to Install File. On the new screen, go to your dol and press A to install it. Wait for it to install and return to the main menu.
4. Now go to Settings. We need to change 2 things here:
Change Autoboot: -> Installed File
Change Return to: -> Autoboot
Save the settings and restart the Wii to see the result.
Note that you can now only access the system menu trough Priiloader!