How can I use that to find out the point by point score for past matches?
I think only Grand Slam matches on the biggest or 2nd biggest court are available because PointTracker relies on the cameras being used for HawyEye.
(not working, they took the PointTracker information down
Try for other Grand Slams accordingly.
You see the list of matches. Click on the match and a window will pop up which will show you all the scores of the match point-by-point and how the point was played.
It should work like that for the other Slams as well.