Great post, many thanks. It was a real lifesaver. I had inherited an early model G5 with Tiger (10.4) and a single layer DVD drive. I managed to track down an ISO image of Leopard but couldn't figure out how to install it until I found your post.

A couple of clarifications that may help others:

Step 4: Drag the DMG file if that's what you have. (This may be obvious but I'm a Mac noob, so wasn't sure).

Step 7: You want the partition for the destination drive (the one you copied the image to in Step 4). The instruction in the original post is a little confusing.

Step 9: You'll see a long list. I had to go to the second page in the list to see my device. The root of the path was much longer than "ht" (something like "ht03,f2000000" - sorry, I didn't write it down). You have to use the entire string. In the example, "disk@2" is a child of "usb@b" - it will appear nested under usb@b in the listing (the example makes it look like it's at the same level).

Step 11: The first dir command only shows you the top level path. The second example is the one you want to use.

After installing Leopard, run Software Update to get further updates to the OS and other Apply software on your machine (Safari, iTunes, etc.). You may have to run Software Update a couple of times. to get everything.

Thanks again. My Mac is very happy to be getting this update.