No, the 222/222k does not have software to turn it into a DVR or use an EHD in any way. IMO, it's unlikely that this will ever be an option, due to the throughput limitations of the USB interface. The 211s are okay with a single tuner, but recording dual tuners while watching a third likely wouldn't work via USB.
Besides, why would Dish enable it when the 622/722 exists? They don't make a single-tuner DVR, so the 211 made some sense, but I don't see any need for a 222 DVR.