The examples used hard-coded values or defines to convert digital pin number to interrupt in calls to attachInterrupt and sleep. This has confused several people, most recently in https://forum.mysensors.org/topic/3880/gw-sleep-on-battery-powered-magnet-door-switch/ Let digitalPinToInterrupt handle this work instead.
For information on installing libraries, see: http://arduino.cc/en/Guide/Libraries