I have developed some changes to the firmware that allow the display to be driven in synchronous serial mode. In this mode, you present the 8-bit command/data stream to the display by shifting out each byte, MSB first, on a data line and effecting a falling edge on the clock line after the data bit is valid. The maximum clock rate in this mode is about 50KHz, a transfer rate equivalent to about 62.5K baud. Note that some microcontrollers like the BasicStamp and the BasicX BX-24 have built in library functions for shifting out data synchronously.
This mode is useful if you don't have an RS-232 serial port available on your microcontroller or you just don't want to use it for communicating with the display. Note that this interface is "write only"; it is not possible to read data from the display. Additionally, when using this mode, the push button support in the firmware is disabled.
By default, the modified firmware operates just as the original firmware does. To request clocked serial mode, you hold pin 13 of the panel connector low during startup. This is most effectively accomplished by simply grounding the pin. The other connections are as shown in the image below.
The source code base for the changes is jw002.asm, CVS revision 1.13. The modified source can be downloaded here and a diff showing the modifications may be seen here. The tools necessary for building an Intel .hex file from this source may be obtained, along with the original source, here.