It would be very nice if one wasn't restricted by the need to fit a bootable image on a floppy and use that to make a bootable ISO, as is done in Maragda. We can get around this by using ISOLINUX, which is based on SYSLINUX, as used to make the bootable floppy in Maragda.
This is the sort of thing we do:
mkisofs -o output.iso \
-b isolinux/isolinux.bin -c isolinux/boot.cat \
-no-emul-boot -boot-load-size 4 -boot-info-table \
<root-of-iso-tree>