1. Open up the Internet Channel on your Wii. If you don't have it, download it from the Wii Shop Channel.
1. Go to flashhax.com in the browser and bookmark the page.
1. Open the site from the bookmark. It'll then proceed to download and load the HackMii Installer. It may take some time as it is downloading the installer over the internet.
If the HackMii Installer doesn't load and it instead freezes (you can't move your cursor), please repeat step 3 until it works.