There's a library that comes with the sample code which inclues epdif.h and epdif.cpp. Extract the "libraries" folder and put it in your Arduino library sketch folder (~/Arduino/libraries). Yes, you'll have a folder called "libraries" inside another folder called "libraries" but it worked for me.
Seems there's a case-sensitve problem with these libraries. I changed the following:
In epdif.cpp change "spi.h" to "SPI.h"
in epdif.h change "arduino.h" to "Arduino.h"
Change the pin assignments:
While ediitng epdif.h, change the pin mapping as follows: