Can I achieve orthographic lighting in Blender? I define orthographic lighting as a single light source that cast a shadow at the same angle no matter where the shape is? Either in front or behind the lamp shading is at the same angle. 

Conditions: Blender render, toon shading (non gradient shading), and you cannot node any objects only the lamp. 

Can this be done?
Use a Sun Lamp
Form the blender manual:

A Sun lamp provides light of constant intensity emitted in a single direction.
This direction can be changed by rotating the Sun lamp, like any other object, but because the light is emitted in a constant direction, the location of a Sun lamp does not affect the rendered result (unless you use the “sky &amp; atmosphere” option).