With the limited command set of something like the display Rob linked to, it wouldn't be too hard to write a program to 'emulate' it using the Empeg's display.

Basically you would open the serial port and wait for incoming data, figure out what needs to be done (based on the command set of the display you're emulating), and do that thing on the Empeg display. You'd probably want to use vfdlib and maybe make yourself a custom font that matches MO's.