Since I don't think it's been posted explicitly anywhere, it should be clarified that you should uncomment both the const and the setProperty lines corresponding to the properties you want to enable, as well as the &newPosition argument and the ScopedLock.
For example:
0b58c138-2c63-4886-8e23-a2c23480d848-image.png
The object is a native script object, so you can just go Console.print(trace(Engine.getPlayHead())); to test it.
Also the TransportHandler exists now which you should probably use instead, but it lacks some options like differentiating between playing and recording.