cattledog:
If you can attach the external interrupt to the pin, you can use digitalWrite() to set it HIGH and LOW and the interrupt will be triggered.
Another option that might be more appropriate for the testing the OP wants to do is to connect a jumper from another I/O pin to the interrupt pin and use digitalWrite() on the other I/O pin.
Even better, use a second Arduino to simulate the yet-to-arrive device.
...R