Stereo rendering for HTC Vive

I am trying to experiment with VR in panda3d, however, I can’t seem to get the stereo rendering to work. The current documentation says it should automatically make it a stereo display with the proper config options.
For testing I just imported the roaming ralph terrain.
Using this code

loadPrcFileData("","framebuffer-stereo #t")
loadPrcFileData("","side-by-side-stereo #t")

class VRTest(ShowBase):
    def __init__(self):
        self.testModel = loader.loadModel("models/world")

I do not get a stereo display
Instead I still just get a mono display.

Is there also a way to render to the HTC Vive direct mode?