Please download the file from the site I linked you and place it on your SD.bootmii isnt on my sd card?? its just in the homebrew channel
Launch it.
For this you'll need WiiMote, not Gamecube controller and make sure there's nothing connected on your Wii (no USB OR MEMORY CARDS OR GAMECUBE CONTROLLERS)
You should see a "SCAM NOTIFICATION PRESS A TO CONTINUE"
Once you press A or 1 you'll see this:
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Let me know when you're seeing that screen.