Once you've reached Las Terrenas, take a Taxi or Guagua leaving towards EL LIMON and ask the driver to stop in "La Barbacoa" at "Calle Luna" which is after the airfield of PORTILLO and at about 7 km's from Las Terrenas.

Follow "Calle Luna" for about 200 m until you see a yellow house on your left. That's the one!
 

The public guagua runs daily, every 20 minutes to or from Las Terrenas to La Barbacoa.
In Las Terrenas you will find a variety of vehicle rentals for cars, quads, scooters...
Very reliable motoconcho service is available upon demand.

If you come by car, please do not try to find it at night.
Driving at night is in any case NOT recommended in the Dominican Republic.