First, make sure both Macs are on, awake, and connected to your local network. On the computer sharing the Snow Leopard disc (this computer must be running OS X 10.4.10 or later, as well), open the Sharing pane of System Preferences and enable DVD Or CD Sharing. (If the hosting computer is running OS X 10.4.10 through 10.5.2, you'll first need to on it.)

Next, on the computer on which you're installing Leopard, open a new Finder window and select Remote Disk in the sidebar; the computer sharing the disc should appear to the right. Double-click the computer sharing the disc; you'll see a Connected message, and the Mac OS X Install DVD will appear. (If the computer sharing the disc has the Ask Me Before Allowing Others To Use My DVD Drive option enabled, you'll see an Ask To Use button; click it and, once the request is approved, you'll see the Connected message.) Double-click the Install DVD icon, and then double-click the Install Mac OS X icon that appears.

From this point, the installation should proceed as described above, albeit more slowly: installing Snow Leopard onto a 2009 MacBook Air from a 2009 Mac Mini over an 802.11n network--with the Nearby And Popular Printers, Additional Fonts, X11, Rosetta, and QuickTime 7 options enabled, and Language Translations disabled--took just over 56 minutes.

If the new installer is so good, why would you want to erase your drive first--a process equivalent to the old Erase and Install option?