I'm bumping into this two years later, and good news is that it's coming soon: https://github.com/NREL/EnergyPlus/pu....
In the meantime, I can propose another (untested) workaround.
The major issue with the workaround by @MJWitte is that there's no easy way to model the "heat recovery" (when you need both cooling and heating at the same time), which is the principle advantage of the so-called 6-pipe heat pump systems.
I think another alternative would be to use a CentralHeatPumpSystem. You probably know already that this object is meant to model geothermal application, but it means it expects to have a condenser Plant Loop.
You could put a District Heating and a District Cooling, and a pump, on the condenser loop, making sure they have infinite capacity, but you'll have to zero-out their consumption. Then you put a SetpointManager:FollowOutdoorAirTemperature on the supply outlet.