i shared a internet connection with my Xbox using my Beige G3 AIO with the Xbox hooked to its ethernet and the Beige G3 using wifi. i kept running into a DNS error cause i was using the wrong IP address setting on the Xbox. below is what i dd to get everything working.

in OS X keep the internet sharing you have set

here is what you do

in OS X open terminal and type ifconfig en0 (thats a zero) which will give you the IP of the ethernet port and other info.

manually enter the DHCP info on the Wii, set the IP of the Wii one number higher then the IP you gained from running ifconfig en0 (a example is if the results show you 192.168.2.1 set the Wii's IP to 192.168.2.2). then set the gateway to the IP you seen when running ifconfig en0. it should be using the mask of 225.225.225.0 and enter that as the mask in the Wii.

once that is done you might need to get the DNS server your computer is using and manually enter them in to the Wii as well. in terminal type dig and after a bunch of text scrolls by, you'll have a line starting with SERVER near the bottom, the IP address in that line is the DNS server your computer is using and put that into the primary and secondary lines as the DNS in the Wii.

after that it should work, i did that and my xbox connected to live just fine. the same should work for the Wii

if you need more help just ask, let me know how it goes.