The Mii corrupt and being deleted error is fine.
Its a "sideeffect" of pegaswitch. Its supposed to be there (probably.
).
And no - you dont need a Mii, or a Nintendo account for that matter.
What you are looking for is a 2000-1337 error, after "Install" went through successfully. After that you short press power, and the system reboots. Then you get the Mii error. Then you go through the process to hit "Run". If "Run" completes successfully, you get a notice, that the screen/app is being closed, confirm with OK. Then you have to wait for several seconds (system freezes for a short while), after that hit B (back) until you reach the home screen. On the home screen enter the Album (Gallery, Images, ...). At that point HBL should launch.
If it doesnt (and Run went through cleanly), try to run "Run" again.
If you get into a fail loop ("Run" doest do anything), reboot, and try again. (Maybe even try Install again, I did - but that you need to is not confirmed as of now.) The entire experience (launching HBL) is quite hit and miss atm. Fingers crossed that this gets ironed out over time.
Make sure you are on 3.0.0 and nothing else, make sure you use an SD card - preferably 32GB max (until it is confirmed to work with bigger sizes), formated to fat32.