Well, Hijack serve(d) up a PNG image of the display over the web server, so there is a way to capture the display. Perhaps that output could be directed to the serial port and then read in? That would avoid having to modify the actual display board. It would seem(from the perpective of someone who's never looked at the code) that it would even be possible write a program that would read the display and output it to the serial port fairly simply without even messing with the kernel. The speed might not be great, but speed is only really necessary for the eye candy.

Sorry if i'm off base here, I'm more just throwing this out as an idea, but it's 3 in the morning so I might regret it later...