I could only find a service manual for the MPC3000 (on archive.org), but the schematic in that one shows the LCD is controlled by an LC7981 display controller.

This interfaces with the CPU's bus and produces very low-level clock & data signals to the LCD panel (CL1/CL2/FLM/MB/D1) - basically a stream of pixels along with synchronization pulses.

Nowadays most "graphic LCD" modules will incorporate a similar chip on-board, so that they can present a simple 8-bit parallel interface.

Capturing + translating the signal would be tricky - it's not _terribly_ fast (240x64x60Hz) but there's no flow-control or error-correction, basically low-resolution video capture