Hi All,
I've had great success using the method caecarvalho suggested - however I have just run into the issue where the transparency setting in the Vray material editor only adjusts the brightness/contrast of the material i.e. 0.25 gives a washed out look, but no translucency. The Alpha layer still makes the correct areas 100% transparent.
This seems to have happened for almost no reason i.e. models which have previously rendered perfectly now don't, and as far as I can tell there have been no significant changes to the models or to either the SketchUp or Vray programs.
Any ideas?