Actually, the kernel currnntly DOES flash itself "out of existance" with the existing mechanism.. the flash copy can be replaced while running with no issues.
An ethernet upgrader is not so much a Hijack project, as a project for the platform from which it will be run (Linux, Windows, Java). The bits and pieces needed to support it are already mostly in place in Hijack (or perhaps ALL of them are in place).
(1) overwrite a filesystem with a new image: just FTP to /dev/hd*
(2) upgrade kernel: already there
(3) reboot: already there
I'm not that familiar with the other steps.. what else is there?
Cheers