if you can't install bootmii on boot2, you have to use priiloader to autoboot HBC or another homebrew.
install priiloader
press Reset while booting the console to go to priiloader menu.
find the boot menu and you can choose to boot HBC directly.
You can also install a dol located on your SD card, it will be copied to the Wii memory and will boot automatically at launch.
if you use priiloader 0.7, some application requiring AHB access will not work. You'll have to install 0.8beta