[jdmuys]

Actually, I found a way which works.

The solution is to create with Disk Utility a new read&write disk image with a size small enough to be burned to a DVD-R(W). Disk Utility proposes the largest such size, and this is what I chose.

I mounted that destination image on the desktop: it works as a read&write volume.

I mounted the source too-large-to-fit-on-DVD-R bootable disk image on the desktop: it shows a locked (read-only) volume.

Note that source is larger than destination: a full backup would not fit.

I used SuperDuper to make a full backup from source to destination, while adding a "Ignore" command to script. I omitted enough to make sure the remaining stuff to copy will indeed fit on destination, and also making sure nothing crucial for bootability was omitted.

The backup proceeded without error. I unmounted destination, and burned it on a DVD-RW with Disk Utility.

Acid test: the resulting DVD-RW did indeed boot correctly on an iMac Core Duo.

So you're wrong: it can be done ;-) I just did it.

JD

Specifics: source was the Leopard seed. Omitted was the XCode directory, which can be installed later.