It has been requested a lot recently, and is on our ToDo list for an upcoming version of Krakatoa.
In the mean time, your workaround would be to render 6x 90 degrees cameras to combine into a 6x1 cubic strip in post, and use some 3rd party software to turn that into a LatLong projection (a.k.a. EquiRectangular projection en.wikipedia.org/wiki/Equirecta … projection ). Obviously it is a lot more complicated than rendering just once.
Some VR systems like GearVR and Oculus actually prefer 6x1 cubic strips for left and right eye, and V-Ray supports that format too, so we are looking into matching its output in both cases. Note that the cubic strip format can express the same data in less pixels compared to LatLong spherical panoramas.