is Zejola referring to this effect? http://www.hdrmill.com/HDRI%20with%20Vray%20Tutorial/HDRI_MaxVray01.htm
like when you get the v-ray infinite plane to receive the shadows, but the plane in itself is invisible and lets the background/HDR shine through?
this tutorial doesn't work http://www.ehow.com/how_7369443_vray-sketchup-tutorial.html and that's a pity, i could use this effect 😕