ok, I'm not too sure as to how I did it but I'm now getting the option to allow ICS when setting up an adhoc, I'll try to explain it but its a bit vague. So I went to the network connections page and right clicked on the internet connection and chose diagnose. after the program finished checking...
i'm having the same problems but I may have partially figured it out. when i go to the sharing tab inside the properties of my internet connection it says as the Home networking connection a different name than the one that the ad hoc connects to and i can't change it to the right one.