Just install it inside the C:/Program Files/Rockstar Games/Grand Theft Auto IV/common/data.
The Dashboard view is replacing the hood view/trunk view.
If you hit something, you'll probably see a bit Niko's head (but it's as far as I can go without loosing interest of a "dash" view.
For certain vehicles, the view isn't that great (it's playable but almost useless).
Maybe something else but I have checked each and every vehicles and they look OK.