The script in here is designed to help you create custom camera path movement with spline curves. In order to save them please follow the instructions below.
Hit U to make a new point, P to jump off the path, and L to change the tracked object.
Then, open web console and search for new THREE.Vector3 and copy all those points to a notepad. These are the spline curve points that will go into the js file for your custom camera path. Next, search for Tracking Box in the console to grab the vector points of where you placed the point of focus object (L to place).
It's a good idea to keep the base script and the custom spline points separate. So you should have something like this in your custom camera path site:
See https://vesta.janusvr.com/spyduck/desert-town-blocks for a finished example world.