Internet sharing in AP mode?

[macsforme]

I have a Macmini1,1 running Snow Leopard with Internet Sharing enabled so I can use wifi on my iPad and iPhone (I really have no need for wifi otherwise). It appears that when this is enabled, my mac runs as a router, assigning IP addresses in a totally different subnet than my home network to my wifi devices. The problem with this is that I want my wifi devices to be on the same network and to be able to access all of my devices plugged into ethernet, and also to be able to do iTunes wifi syncing, etc. A google search for a way to do this has been unfruitful so far. I also recently bought a Macmini5,1 that I am getting ready to transfer data over to which will run Mountain Lion. Is there a way to share access to my mini's ethernet connection over wifi in simple access point mode, without it having to use NAT and act as a router?