I think you may need a dll, because you must first of all change the main render target to a floating point texture. Maybe this can be done with pro, but i dont know..

Basically the process you use is this:

1) change the main render target to a floating point texture
2) render the scene normally to the flaoting point texture.
3) do the post-processing like tone-mapping, bloom etc.
4) switch the main render target back the the default
5) then finally draw the LDR image using a screen aligned quad.