A few years back I wanted to do this with a compact Mac and found an article on Low End Mac that recommended using System Picker. The link to that utility was to the Apple Developer site and long broken. I finally hunted it down on an ftp server in Finland.

Anyway, I wrote an article about the experience on my fledgling blog devoted to classic Macs and you can find it here:

http://classicmacs.org/2008/12/system-picker/