anng3,
I presume that's Sosua town you're talking about.
It's within walking distance alright. I've walked up there quite a few times from La Puntilla.
It'll take you less than 30 mins from the centre of town.
In my opinion it's an easier walk than drive!
You could lose a 4x4 in some of the potholes

Of course don't walk up there when it's raining.
Mack.