I think it's better to not use the interrupt features until you get the basic functionality working. Do you only get 0s even when you move the board around?
I didn't realize that the board you're using is not the same one as that SparkFun tutorial. I see now that it does have the pins labeled INT0 and INT1, unlike the ADXL345 breakout board. If you are still having problems I'd try to use the tutorial linked from your board's product page:
http://bildr.org/2012/03/stable-orientation-digital-imu-6dof-arduino/