If you want to do the scripts yourself you can use https://discuss.eroscripts.com/t/motion-tracking-funscript-generator-v0-1-x/28117 (Standalone or as addon to OFS). Once you are familiar with the tool the things are pretty straightforward - just mark 3 or 4 grey and colored bars and the tool will do the rest for you:
When I was doing the scripts I found out that it’s much easier to start tracking from the middle of the stroke instead of starting at the highest / lowest point, the tracking was more accurate as well. Also if you can use higher framerate video (they sometimes have videos in 60fps) and it shouldn’t lose tracking area too often.