I'm trying to make minor adjustments to the bootcd.iso but no matter what I
alter I get an image checksum error when I attempt to boot from my new cd.

I've tried MagicISO, WinISO and even manually using my Linus box (the way I
used to do it with zen 4)

All I'm trying to do is change the default load option in isolinux.cfg to
manual instead of linux.