It is possible! I did it just today! All you have to do is use the AnyRegion Changer here:
http://wiibrew.org/wiki/AnyRegion_Changer
Put it on your SD any then run it. Preferably the homebrew channel.
Change the Language Setting to Japanese. Change the Game Region Setting to Japan. The Shop Country code to 1. And Finley the System Menu Region to Japan. Choose save settings then reboot the Wii. Go to the options menu and choose WiiConnect24 and agree with the terms of use (its in Japanese so play around with the options). Then go to the Shop Channel and buy the Nintendo Channel and there you have it. Im a huge DragonBall Fan and I downloaded the DragonBall: Origins Demo today! Its soooo fun! If you have any other questions please ask! Also this does NOT brick your Wii in any way or put it in danger.