This is going to be a bit tough to explain, but I'll give it my best shot.
The complicated part of going the Moca route, is getting through Moca itself.
There is no doubt that the road is better and safer and has less traffic than the Caretera Turistica.
So here we go.
From the STI airport, as you intersect the main Duarte highway, you have to cross, turn left, in a South Easterly direction.
You drive approx. 5 minutes to a left hand turn, at the first sign for Moca.
You take this road to it's end (approx 8 to 10 minutes).
It intersects with a North-South small highway, at the South end of Moca.
Here, at the intersection (traffic light) you turn left, heading North, and within a couple of hundred feet, you bear right at a split in the road.
You will now be on a narrow road going North, through Moca.
The next turn is the one you must not miss and is a bit harder to identify.
First clue will be that the road you are driving on, widens out a bit and lowers as well.
You will come up to an intersection that has only left turn, and the opposing traffic to you has a speed bump. There is also a large prison on the North-West side of the road.
At this intersection, you turn left.
Shortly after, it starts to go down, reaches the bottom of a hill, where there is a traffic light, and you continue on straight.
You will now be at the North side of Moca, heading North and there will be less houses and more commercial establishments.
After driving a few minutes, you will come to an intersection where the highway bends left, and there is a right hand turn off, which is almost in a straight line in which you were heading. As you take the right hand split, you will see a small gas station right there on the right hand side.
You drive along this road for approx 7 or 8 minutes, at which point you will come to the first major intersection, in front of a gas station on your left.
Here, there should be a sign for Jamao or Sabaneta, and you turn right there.
From this point on, you're laughing. It's straight (windy road, of course) to Sabaneta on the North coast.
At Sabaneta, when you get to the main highway, you turn left and will be less than 10 minutes to Cabarete, and another 10 minutes to Sosua.
If you are asking for directions along the way, just ask for Jamao, see which way they point, and keep on going. To sit there and listen to a long story in a language you barely understand is just a waste of time.
If you have missed any turn offs and they point in the opposite direction that you are driving in, turn around and keep asking for directions every couple of minutes, seeing which way they point.
A smile and a "Gracias" is all you need.
If you print this out, you should be able to make it through, problem free.
If you need a break along the way, when you are almost at the very top of the climb up the mountain, you will come up to a rustic looking restaurant on the right hand side of the road, with a fairly big parking lot, called "Rancho la Cumbre"
Best dang "cafe con leche" I ever tasted, and if you want a snack, the chicken or veggie crepes are awesome.
The view, service, atmosphere and food are awesome, and the prices are really cheap.