mbootpack is a tool that takes a Multiboot kernel
and modules (e.g. a Xen VMM or a xen-linux kernel
and initrd), and packages them up as a single file
that looks like a bzImage Linux kernel. The aim is
to allow you to boot Multiboot kernels
(specifically, Xen) using bootloaders that don't
support the Multiboot standard (i.e. pretty much
anything except GRUB).