Using Microsoft Internet Sharing on Heterogenous Networks?

spoonboy42 asks: "A friend of mine wants to try running an Apache server on Linux at his home, and he's asked me to configure it for him. He uses Windows 98's Internet Connection Sharing to allow the computers on his network (all Windows 9X clients) to share access to his cable modem. I told him to install a Linux or BSD proxy server, but he doesn't want to alter his network just yet. Ordinarily I would think it impossible to use ICS under Linux, but when I tried a QNX demo disk in one of his machines, it autodetected all settings and was able to use the Internet. Does anyone know a way to make Linux do the same thing?" Assuming that this is possible (I still have my doubts), what steps must be taken to get non-Microsoft clients working with Microsoft Internet Sharing?