The PPM out connector only has Rx, Tx, and Gnd. You also need a Vdd connection. so you'd need to connect a wire from a supply on the Tx to the dragon module. you could either get a replacement connector, and unplug the 3-pin audio jack, and replace it with a new port, or you could use an audio cable to get at the PPM signal.
At that point you should be able to drive the DL module by putting the Tx in 'PPM' mode. Note that this will turn off the radio, which should be ok.