By using a patched copy of AC:CW with the Wiimmfi DNS and a WEP router, and going on the heart section of the inventory screen.
I currently host the DLS1, GAMESTATS, and Peerchat server for Wiimmfi. if you have any issues with leaderboards (excluding MKW!), Mystery Gifts or other in-game downloadables, or Pokémon Wi-Fi Plaza, I can try to help!