To get the best results, you should punch a small hole in the left side of the body where the door is and push the led through this hole. The sensor will only pick up your laps if the led is pointing directly at it. If the led is at an angle, behind window tint, you drift by the lap counter sideways, etc. it will not pick up the lap.
I've been debating on whether to get the pc cable and software for it. I'm not sure I want to tote along a laptop to the track.