I have released a test version of syslinux with support for "ipappend
2", which causes the boot interface hardware address to be passed using
a new "BOOTIF=" command line option (capitalized to indicate that
it's
not really a kernel option.)
Please test it out and let me know if it works.
ftp://ftp.kernel.org/pub/linux/utils/boot/syslinux/Testing/
-hpa
P.S. Thanks to Stan Smith for providing a patch for the boot interface
issue; I didn't actually use your code, but it made me look at a few
things which needed to be looked at.