how can i make a shadow cast which is direct to the camera? BI

blender internal
i want to make a scene of something like this:

so there is a direct light source behind a thing that casts a shadow, i want volumetric to show the shadow path, but i can’t seem to get the size and the settings right.
it would look something like this:

but with the person on a very very high tower, but i also want to show the tower too…
how can i do that?