I doubt that'll work, because the game most likely won't check if there already is a savegame, but if the update is already installed...maybe i'm just stupid, but maybe it is possible to start the game if you already have a savegame of it on it!
btw, I just unplugged my Wii while updating (the progress bar was at about 20%, so that seems to work fine, too) and every channel is still working fine...now I just have to try the BrickBlocked patched Metroid Prime 3, which I'm still burning (lame ass 4x recorder