I'm not sure, but i've heard that similar hacks work since the "Wii mode" is essentially a Wii and doesn't have extra security measures. You may want to confirm on a forum/board that is actually associated with these.
Btw, if you like BrawlPlus, you should look at Project M. Pretty much a better experience all around. --- RoB IGN: gmquinto
Why would you want to play Brawl on the Wii U? Gamecube controllers all the way! --- http://backloggery.com/Zashule : Last 1000 Megamind : Last 200 Monster Island WP7 Current XBOX LIVE GS:139,928 Next Goal: 140K GT: TBreit