That tool works fine for the '07, but as has been mentioned in this thread will not work on '08's because of the angle on the sensor.
Take these steps for an easy removal of the sensors:
1. Warm bike up.
2. Spray some penetrant (e.g. WD-40) on the base of the sensor and let sit for a few minutes.
3. Work the sensor out slowly, repositioning the socket every 1/2-turn or so making sure the wire doesn't bind or twist. If the sensor resists don't force it, but spray on more penetrant, turn the sensor in a bit, spray on more penetrant, then continue to remove it. If you force it you may ruin the threads on the stock sensors.
4. Before installing the PCV sensors apply some anti-seize compound on the threads, but don't get any on the tip or anywhere that protrudes inside the pipe.