The Nintendo Wii comes with an audio-video cable for standard plug-type connections to a TV. You can connect the game console to an Apple iMac, instead, using an adaptor cable to transform the video signal from the Wii cable into a digital video interface (DVI), which is compatible with an iMac. Use a separate Y-adaptor to convert the two audio cables from the Wii into a single stereo mini-plug connection for the iMac's audio port.
Connect the single plug on one end of the audio video cable supplied with the Wii to the port on the back of your game console.
Connect the red, green and blue video plugs on the other end of the Wii cable to the matching jacks on the DVI adaptor cable. Plug in the other end of the adaptor--which has a rectangular plug with three rows of metal pins--into the DVI port on the back of the iMac.
Connect the red and white audio plugs on the Wii cable to the two jacks on the Y-adaptor. Insert the red plug in the adaptor jack labelled "R."
Insert the mini stereo plug on the other end of the Y-adaptor into the audio line-in jack on the back of the iMac.