Looks interestingly like something I did a couple of years ago. I
believe Spectra Linux 1.2 was the last I did with "CD-ROM multiboot" as
I called it. I used it mainly to offer multiple language choices right
from the start and parted boot floppy.

I stopped when RH started using isolinux, because I thought that using
floppy images would be too much trouble and El Torito supports only one
boot program type of image.

While El Torito sets no practical limit to the number of boot floppy
images, 8 is the highest number I have seen supported in BIOS (Award). I
added Smart Boot MAnager image to my older distros
(http://btmgr.sourceforge.net, the project seems quite dead, but the
product is still perfectly usable) to give multiboot option also to
Dells and other machines which can boot only the first boot floppy image.

I might use that trick again in the future, so I am interested in the
problems you might have and I might be able to offer some help.

--
Raimo Koski  http://www.lineox.com/  http://www.raimokoski.com/