HI!
Obviously you are knowledgable about the implications of mixing close/non-Free versus open/Free software. See this posts where I dscribe the problem of creating a remaster with VMWare on it. http://www.knoppix.net/forum/viewtop...?p=80161#80161

I am pretty sure you can not bind what was once a freely distributable CD of freesoftware to the closed distribution terms of a non-free package. So the only solution I see is to explicitly allow redistreibution of your demo files/binaries and explicitlly deny modficiation. I would create a warning or caution message that would appear in at a minimum of 4 places so there is no possible chance that the message could be overlooked:
- Boot screen where cheat codes are entered
- During the loading process where it detects the systems RAM (in the /cd-root/boot/isolinux/minirt.gz compressed loopback ext2 file, in the linuxrc script)
- When the KDE desktop if fully loaded Konqueror comes up with a welcome to Knoppix message
- When you run the demo program.

"ATTENTION! This CD is based on open source & free software. With the exception of *your-demo-program's-name*, you may redistribute & modify all other programs under their respective FOSS license terms. *your-demo-program's-name* is a product of *your-company's-name* and does not allow modification but does allow redistribution by copying the CD. Visit *your-demo-program's-name* website for more information "

As with all things on the internet, I am not a laywer. You may need to seek legal counsel.
I hope this helps.
James