The wireless hardware on the Wii is a BCM4318-based daughterboard that connects to the Hollywood via an internal SDIO bus. Information on this device is scarce.
|Access size||unknown/32[check] bits|
|Byte order||Reversed Little Endian|
See http://www.gc-linux.org/wiki/Wii:WLAN for additional information.
IOS's WL driver contains a lot of code that matches up with the code in the Android broadcom.git repo, specifically bcmsdh.c and bcmsdstd.c. That driver, combined with the knowledge that the BCM4318 is connected to the Hollywood via a standard SDHC at 0x0d080000, is probably enough to get WiFi working.