They're not directly supported yet. There isn't any software out there that supports the PVR other than Arcsoft showbiz and total media extreme (which are the same thing really)
Jim has stated that he intends to pickup a PVR sometime soon, so he can add support to OBS.
For now, you are limited to screen capping the Showbiz preview window.
Also, If you stream using a desktop computer (rather than a laptop) then I would highly recommend selling the PVR, and buying an internal capture card, like the Black Magic Intensity Pro, or an AverMedia Live Gamer HD. (Intensity Pro being the cheapest)