Here's a simple directional blur test we tried a few weeks ago, its a similar method but with an offset in U/V used to create the blur.

You would need a similar setup but use a scale in UV to create the 'radial blur', on each image the UV scale is getting smaller.

We used only 8 images but the more you add the less stepped the resulting blurred image will be.

jolly

Jolly : CP Store :