The new type of vray light - dome - is analogical to the standard max skylight. And as such its position and scale does NOT matter to the lighting solution. What matters, however is the rotation of the light. If you want to light the scene straight from the top, your local Z axis should be upwards.
Here is a small example:
adaptive subdiv 0/3
gi primary - irrad low preset
gi secondary - monte carlo 1 subdiv
320x240res
