Patrick (pca) did it as an add on board inside the empeg for a private customer. It used the IDE bus as the interface to another ARM (something like that) chip on the daughterboard. This then generated the video output.

The problem with this was that it was privately funded by somebody and therefore the design can't be given away. You could employ Patrick to do it again but I believe it involved very large sums of money to initially create. The new board would probably also involve an equally large amount of money.

I don't think the I2C bus in the ARM does fast mode and is therefore limited to 100kbit/s. The serial port however can actually go up to 230k so that would be the simplest way of interfacing it. You'll have to do compression still as 230kbps is still not fast enough to send uncompressed full frame and full speed for the display. If you don't mind the visuals being slightly jerky then you don't need to mess around with compression.

One of the FPGA boards I've got could do it but they're not cheap and I personally don't have the time to do it unfortunately.