Follow this guide to keep cioscorp
Tutorial:How to Run HackMii Installer with cIOSCorp Installed
Or unistall cioscorp, then you should be able to install the hackmii installer.
Download cIOSCORP v3.4 Uninstall (LU64)
Download bannerbomb 4.2 only
Backup your sd-card and format fat32.
Extract bannerbomb to sd-card
Extract cioscorp uninstall to sd-card, rename its dol file to boot.dol
Do not put the sd-card in the wii
Power on the wii
Push the sd-card icon (on the main wii screen, not from settings)
Uninstall cioscorp- read and follow the directions
After that proceed to the 4.2 guide
Full hacking guide for 4.2 system menus!!!!
Best of luck