There's really not very much magic involved. The root filesystem is just a collection of directories and files. The kernel is just a binary blob, usually stored in /boot. You perhaps need an initial ramdisk tailored to your configuration, but that's usually just running a script. The only really arcane bit is bootloading the kernel. With modern x86 systems EFI does it, and so you just need a correctly formatted fat32 EFI partition.