Thank you all for the replies! I got it to work and it looks like it was helpfull to more people as well.
However, after messing around a bit the parameters, I've got a follow up question (I hope this is allowed..).
As Justin and Mark suggested, it does work in the Edit Light... menu using Renderworks, so I started rendering with Renderworks.
For completness, I looked up the bulbs we use to get the right amount lumen they produce and use that in the menu mentioned above.
But when I do this the brightness blows up and I have to dial the dimmer parameter down to 15% to get something realistic.
Do I interpret the datasheet value wrong? Or is there something happening in VW?