Comment 279 for bug 930447

lkml: "grub is jumping to the 32-bit entry point and skipping the entire real mode setup code. Bad grub."

You don't need to build a syslinux bootable iso. You can boot the kernel from Grub in 16-bit mode by using the linux16 command http://www.gnu.org/software/grub/manual/html_node/linux16.html and initrd16 https://www.gnu.org/software/grub/manual/html_node/initrd16.html

According to the discussion on LKML, linux16 is now the default on Fedora, and should be used by other distributions.

(If you still want to build a custom syslinux bootable system, just for fun, see the instructions at http://willhaley.com/blog/create-a-custom-debian-live-environment/ - it's about 25 lines of code in total, and not difficult to follow)