You probably have bootmii installed and don't even realize it.
v0.7+ of the hackmii installer installs bootmii automatically when run. v0.7 of the hackmii installer installs v1.07 of the HBC, so if your HBC is running v1.07 or higher, then u have bootmii installed as IOS.
Do this before you try anything else.
download this:
http://static.hackmii.com/bootmii_sd_files.zip
extract\save the bootmii folder from above to your SD card (i.e. SD:\bootmii\). Then put the SD card in your Wii and turn it on while holding reset to try and access the priiloader menu. If the bootmii menu pops immediately (before priiloader), it means you have bootmii installed as boot2 (which is great news). If bootmii does not appear, try launching bootmii from the priiloader menu (if bootmii isn't an option it's cuz you're running an older version of priiloader, let us know and we'll get you to boot a file instead that will launch bootmii if installed).
Once you're able to access the bootmii menu, u can use a GC controller or the power\reset buttons on your Wii to create a nand backup (go to the settings icon, then select the picture of the nand pointing to the SD card).
If you can't access bootmii using the above method(s), then it's not installed. You should download the hackmii installer from the bootmii.org webpage and save the boot.elf and bootmini.elf to the root of your SD card. Then install the boot.elf as priiloader's file then load the installed file, this will load the hackmii installer, from here you can install bootmii (let us know if you're able to install bootmii as boot2). If you're able to load bootmii as IOS via priiloader in the previous step, u should load the hackmii installer by launching bootmini.elf via the bootmii sd card menu, and from there u can check if you're able to install bootmii as boot2.
Basically, install bootmii as boot2 (if possible) and\or as IOS. Launch bootmii and make a nand backup. This should be your priority because if you can install bootmii as boot2, u can recover from almost anything all by yourself. If you don't have bootmii installed as boot2, but you at least have a nand backup, you can recover from any brick with DeadlyFoez's help (or by buying and infectus nand flasher and learning how to take apart your wii and reflash your nand). So before trying anything else, install bootmii and make a nand backup!
edit:
Well the same is true for an update from Nintendo. But how likely is it that the power goes out in that moment? I think the last power outage here was 15 years ago and that was announced, since they had to do some work on the power lines.
But yeah a nand backup or at least the keys to the Wii are always a good idea.
You don't need a power outtage to lose power, you could have a clumsy friend who happened to trip on your Wii's power cord. Sounds funny, but I personally witnessed a hard drive fall 3 or 4 feet to the floor because someone tripped on the power cord. Needless to say that HDD was destroyed.
Besides, just because the power doesn't go out frequently for you doesn't mean that's the case for everyone else. I've had the power go out for a split second and come back on probably about 5 times a year. I don't need to worry about that though cuz I've got my important devices plugged into an APS with a battery backup.
I realize that when we help ppl online we don't accept responsibility for any damage that is done to their console, but at the same time we should at least tell the person straight up when there are risks, even if they're miniscule. IMO, we should let the end user brush the risks off as being negligible, and not do it for him.