Sometimes you need to get over the top and look straight down on the subject. In the example pictures above you can see how I have arranged my tripod. The two front legs being vertical with the back leg extended a bit more to make this happen. Naturally mother nature doesnt allow this as we get a centre of gravity problem. To overcome this I have tied a doorstop to the back leg. Any heavy object that is tie-able will do. The lighting was provided by daylight through the window. To light the shadow side of the subject I have simply bounced the light back with some sheets of paper. If you do this sort of thing a lot I suggest obtaining a sheet of white polystyrene from a builders merchant. You may be lucky and find some small enough to get in the car. If you need to cut the polystyrene the cut edge might need taping up with what I know as "gaffer tape".
Just to prove it works I exchanged my trusty old 'Los Angeles Olympics 1984' Canon F1 for the Minolta Dimage 7i and took a snap This is how it looked straight from the camera. To improve things a bit I used a technique described on the Photoshop Heros site. The trick I used was the "Velvia" one where the colours in the picture are intensified to make it look like the effect you got with Fuji Velvia in the days of film (it is still available).