US review copies have confirmed the rumour that you will be able to upload a total of 100 tracks from an SD card into the game to be used as a soundtrack.
You simply insert an SD card with your MP3's loaded onto into the Nintendo Wii's SD slot before you power up the game. Then when the game is loaded hit the "+" button and you will be able to select the SD card on the sound settings. You will be able to set the game to play a single song, randomise all your songs or listen to the default music.
The use of custom soundtracks is good news, particularly if like me you like playing video games while listening to Blondie and ABBA.