How to add a binary file to the .iso ?

For testing purpose, I would like to a add an image of a FS in the ISO build by Ant.
How can I do this ?

resizing the boot disk ?

I have resized the disk by doubling the number of heads
before: jnode.disk.geometry" value="64/16/32"
after: jnode.disk.geometry" value="64/32/32"

I can add my binary files, but I can't boot properly. It stay in the shell of grub.
Is there any other thing to modify ?