If you use the standard cable that comes with the wii you connect the white and red to you're surround receiver. And chose under "wii settings/ sounds " surround. Dolby prologic 2 is probably the one that works best on wii haven't acutely tried.
use the cables and plug into a stereo or something with surround sound. Works for me (only I have 2 not 4 speakers)
i got mine plugged into my x-fi with 7.1 (gotta turn my pc on to have sound) must say sounds very nice.
from a technical point of view the wii dont have surround, but it has dolby pro logic ll and what it does is to fake surround so you could say the wii has it but actually it doesnt