You have homebrew channel installed?
Do you have WAD Manager on your SDcard? If so, you'll see it under the homebrew channel as an option.
(I'm assuming at this point, since you rented a game only released in the US, that you're a NA wii owner, thus using NTSC)
Download these four files, and place them in a 'wad' folder in the root of your sdcard.
RapidShare: Easy Filehosting
Now, boot your wii. Go to home brew channel. Load the WAD Manager. It'll have you hit A to continue. Then you'll see those four files. Go down the list clicking the '+' next to each one to have it install.
That should cover you for everything you need for newer games AND wiiware. The last one is going to install a new Backup Launcher. It will auto fix those pesky 002 errors, AND it will automatically force NTSC for you. So if you have any PAL games they will auto boot in NTSC mode.
*If you don't have WAD Manager, here's a link
Simply make a folder on your SDcard, under the apps folder. Name it whatever you want. Place the 'WAD-Manager_v1.4.dol' in there and rename it to 'boot.dol'. You will then see the option to run it under your homebrew channel.
*edit: If you're confused at all. Just ask. Also, i 100% positively assure you w/o a doubt doing those steps is going to be a million times easier and safer than un-mod'ing your Wii.