Burning bootable CDs

Well, a client of mine seems to be stuck with CD drives that won't boot
multi-session discs, but I still don't want to have to have them insert a
floppy w/ settings.txt on it...

Just on a whim, I extracted the 6.5 bootcd.iso to disk with Nero, copied the
settings.txt into the root, then burned all of the files back to a new disk.
As you probably might expect, this didn't work - evidently burning straight
from the ISO file writes bootable information to the disc, which the system
then couldn't locate.

Is purchasing WinISO the only solution for this? This program will let me
insert files into an ISO image, then recompile (for lack of a better term)
back into an ISO to create a bootable CD? Is there a freeware version of
something that does this?

Thanks again

b