First of all: sorry for the late reply, but I had little time the last weeks.
I'm very interrested about this topic also. But I cant really understant what you did to make it working.
I use isolinux as primary boot loader. Perhaps this is not exactly what you want, but all in all it works without any problems in my case. But I can try to help you using CDShell for a multiboot DVD.
I can customized UBCD to add my own floppy image, also, I successfully add miniknoppix (thank to tutorial) But I'm not skilled enough to create a bootable DVD with UBCD in.
Hmm, where is the difference between a CD and a DVD (except for the maximum possible size of the iso)? Did I miss something?
it can be usefull for example to burn a DVD with the following iso of UBCD, windows installation CD...
Integrating CDs using the "no emulation" boot method to your multiboot CD (or DVD) should be no problem in case the boot loader of such a CD has the size specified in the boot catalog. This is the case for CDShell, Microsoft's bootable CDs etc., but it is not the case for CDs using isolinux such as KNOPPIX (the isolinux boot loader is larger than the 2048 bytes loaded by the bios on boot and it needs some special care to find the rest of its code).
Be sure not to violate any (copyright) laws when integrating other CDs to your multiboot CD.
1st case ("no emulation"):
- copy the contents of UBCD to a directory on your harddisk (reffered to as "root directory" of the mutliboot CD/DVD)
- use bbie.exe from http://www.nu2.nu/bbie/
to extract the boot image from the original CD or its image. (If you use GNU/Linux - the best OS in the world - I can send you a bash script doing the same.)
- copy all the stuff from the original CD to the root directory of the multiboot CD/DVD including the boot image extracted before. A good place to store the latter may be a directory called /boot/bootsec/ and a good name could be bootimg.bin (be sure to use .bin as extension!).
- add an entry to a CDShell menu to boot /boot/bootsec/bootimg.bin using the isolinux module (maybe someone else can give you a hint with the correct syntax of the CDShell menus).
That's it. Create the CD/DVD and be happy. The exact procedure for this last step should be described somewhere else. One last note: when copying the files from the CDs to your disk be sure not to change upper/lowercase letters and be sure not to overwrite files from one CD with files form another CD! If there are conflicts with filenames from different CDs, have a lot of fun solving the problem...
It is possible to create a multiboot DVD with KNOPPIX (or another CD using isolinux) _and_ KNOPPIX showing up with its own boot loader when selecting it in the menu of the primary boot loader. But this is another story. Try the 1st case first.
Please let me know if the hints helped you.