If you purchased the pre-made TT2x harness, it comes with the FlightView TT22 cable which is terminated in a DB-9. Simply plug that DB9 into the controller connector on the harness and connect the USB port to your FlightView system’s USB hub.
Note that you will also need to connect the Power ON pin (13) to a ground pin to get the transponder to power up. This can simply be a permanent link from pin 13 to one of the ground pins or it can be through a switch on the panel. Be careful here – the Power ON pin is NOT the same as the Controller Power pin. If you connect Controller Power to ground you create a dead short. (All other pins on the DB-25 as per the Trig documents.)