Shader: How to map texture on a mesh without perspective/wrapping?

I’m looking to write a shader that takes a texture and displays it on a mesh without “wrapping” it around the mesh’s shape. Basically, I want to create a “paper cutout” effect, where I can feed in a paper texture that is constant and flat no matter which direction the character is rotated/viewed. Could anyone provide me with some direction on how to achieve this effect?

Try the “Detail Texture in Screen Space” surface shader example, here: http://docs.unity3d.com/Documentation/Components/SL-SurfaceShaderExamples.html