that talk about using a small flashlight that is masked with a bit of neutral density filter (which could be nothing more than a bit of exposed and processed film leader) that you can use to flash specific highlight areas. I've tried that - it does work, but it's tricky to get the right amount of contrast reduction and avoid creating an obvious abnormal shadow.
Well I have read about this technique... I will argue that this is impossible to do... If you think about it