You probably can't see Bootmii because it is loading in progressive scan mode (480p), which only works over component. Are you able to boot into the Homebrew Channel? If so, use this to change your video mode from PROGRESSIVE to NTSC. Don't use any of the PAL modes unless you want to fry your TV. If you can't get into the homebrew channel, you can edit bootmii.ini on your computer too, but I don't know the exact instructions. It shouldn't be too hard though. Just open it in notepad and edit the proper line (I don't have a bootmii.ini file on me right now, but it worked for me).