If it has TX and RX pins it is most likely serially controlled. But without more information on how to set up the serial comminication with the display and how to send commands to it, i'm afraid it's impossible to give you any advice.
But try to check here:
http://www.4dsystems.com.au/downloads/micro-LCD/uLCD-128-GMD1/
it might be whar you are looking for