Clean dirt render with no horizon

[AkaBear]

Using the latest version of Vray for Sketchup how would you approach doing an ambient occlusion render to achieve something along the lines of the linked render from cCrisan http://www.ccrisan.be/3D/maq/maq01.jpg

I have tried using a virtual plane but it gives a horizon.
I have turned off GI and/or BG in Environment but still get a horizon.
I have tried boosting GI over BG and reverse.

I have turned GI and BG to white which helped a little.
Also can't seem to get the grey tone range as shown, I thought that maybe in the linked image that they actually toned certain parts rather than a pure ambient occclusion / dirt render.

And simply turing off materials and using a near white for the render does not seem to give anything close.

Any pointers would be appreciated.

[stefanq]

This topic could help, I think: http://forums.sketchucation.com/viewtopic.php?f=322&t=34597