It is very possible, but nobody has bothered writing the small program required for it yet, since upgrades are usually pretty rare.

But now that the Linux upgclient tool no longer works for me (doesn't like my newer notebook computer), I suppose I'll write an upgrader for Linux.

This one works over ethernet, doesn't wipe out the Hijack kernel (unless you want it to, I suppose), and should be much faster than the old serial based one.

Linux / Unix only, of course. But others are welcome to port it.
I'll have a go at it this evening.

Cheers