Hi there vitorboschi,
The Sweep device is only capable of outputting data in 2D polar coordinates relative to itself. See the Sweep manual for more information. Any additional transformations must be applied in software after data collection. Currently the Sweep Visualizer supports limited transformation (only translation and rotation) of the Sweep coordinate system relative to the world coordinate system of the Visualizer (ie: the visible Cartesian grid). This transformation is applied by the Visualizer after the data is collected.
Hope that answers you question. If you are looking to implement your own transformation stack, I'd be happy to direct you toward some relevant reading.