Does anybody know how to hack prestiges on CoD MWR Wii?

I do. But you have to hack some stuff. First you require the Homebrew Channel, which is not buy able on Wii Shop, it's a channel that nor I or Nintendo endorse. To get the channel go to www.wiibrew.org and search BannerBomb, you'll find the details there. After you have the homebrew channel, install the app Gecko OS, the newer version the better. Once done this get the Cod MWR hack pack (Courtesy of Hetoan2), and download it. If your game is a USA MWR, then name the txt file it's in RJAE52. Without the period at the end. Download Ocarina Cheat Manager as an application for your computer, and use it to open up the .txt file you got earlier. These are all codes to the left of Ocarina, do to the bottom and there will be a Prestige Modifier code (Don't bother with the Prestige Cycler). Now you see the code in the middle of Ocarina, change the X at the end to what you want your prestige to be. 1 for first prestige, 2 for second and so on. 10th prestige is a capital A. Then put your SD card that your using for homebrew channel and gecko os and such, and click "Export to GCT", and put it on your SD card, it will make itself a new folder. Now open up your Hombrew channel and Load up Gecko OS. Go into config and set the Hooktype to OSSleepThread, this is vital for it to work. Click 'Save Config" and load the game with Gecko. Now go Multiplayer and your prestige should be whatever you set it to. Sorry for it being so complicated but that's how it's done. I do not endorse any illegal activity with the use of Gecko OS, Homebrew channel or Ocarina Cheat code Manager.