I rember using this technique back in the days of film I was going to look for some shots I did back then but decided I would give it a quick try the garage tonight. These shots are no where near as good as the original post but they give you an insight on how the technique works.
The shots were done with my Canon D60 set at 100 ISO speed on the manual setting f16 and 20 sec exposure.
The camera was set up with the lights on and the focus was set on manual.
I set the camera on the work bench in garage and turned off the lights. Then I pressed the shutter and tried different lighting methods.
First try was with my flash unit. I pressed the shutter and then walked over to the car and fired the flash a couple of times
Then I got a work light out and waved it over the hood of the TA.
Next I added a black screen in front of the light and again walked the light over the hood.
In each of the shots you can see me as a shadow.
If I had a brighter light and played with the exposure you would not see me moving around.
In the garage there is no outside light so the only the lights you use light the shot. When you are outside there will be some ambient light to set the scene and you can set the camera for a very long exposure to use that light and then highlight the car or any other subject. You wont see a black hooded light operator because you don't stand still long enough to show up in the shot.
As the shots in joe74ta's post show with some work you can get some very interesting shots!