Post-Processing Sunbeams blurring

You can get mock-volumetric lighting with some clever tinkering with this, but it looks kind of ugly because it’s not blurred.

http://img29.imageshack.us/img29/3636/volufailtriclighting.png

I was wondering if anybody could write a lua script or something so that the area between the “lighting” is blurred, and looks more like the real deal?