Can the HP Jornada 820C Run Something other than WinCE?

!TorpedoBay asks: "I am looking for an OS to run on an HP Jornada 820C - want to get rid of the CE thing. I know this is a 16MB ROM machine - is there any way to replace this OS with PalmOS or with a stripped down Java OS ala Espial or something else? How hard is it to replace the ROM chip in these devices anyway?"