The HV_PROG connector contains all signals required to do HVSP or PP programming. The signals on this connector is not level-converted, and should only be connected to the EXPAND connector on the AVR Dragon. You could damage both your target and the Atmel AVR Dragon if you try to do HVSP or PP on an external target board. The signal levels on the HV_PROG header are 5V.
The figure above shows the general pinout of the HV_PROG header. The High Voltage programming pin mapping is not the same for all parts. See the HVSP Description or PP Description chapters for more information on the pinout of this header.