Unity spot light attenuation is range-dependant, and vaguely quadratic. So if set to a mystical range property, it'll behave exactly like a point light in Maya set to quadratic.
You can write your own attenuation:
http://unity3d.com/support/documenta...tenuation.html
But it'll NOT work with Deferred Rendering (default is hardcoded into DR like the blinn-phong model).
If you're after just one spot, then try some spotlights, they can be aimed and can use a cookie if you're up for some god-teir cheezing of GI on the floor (render AO on the floor (planar mapped) to a texture, assign texture to cookie in spot light, aim spotlight at floor from way up above, ???, incur wrath of many, many artists).