Cary, the link I provided shows what Mac128 is talking about in explicit detail. Only, I've found you don't even have to change the extension. Mini vMac opens my .DMG files just fine. The link is a PDF and in the PDF is a direct link to the disk images (or you can make your own). It's pretty simple and will get you up and running in no time.

If you have a specific question we can try to help you with that.