FX2 can use the GPIF to connect up to almost any external slave device. The first thing to do is determine the hardware interface between the GPIF and the external memory device. You must decide whether there are enough GPIF address lines available to connect to the external memory device.
Please read through the GPIF chapter in the FX2 Technical Reference Manual. In addition, please refer to the application note, EZ-USB® FX2LP™ GPIF Design Guide - AN66806.