OK, the other kind folk have the basics. Here is the skinny.
Head south from GC. Immediately after you go down the hill into Mariot take a right, ie a little less than 90 deg, at the round-about. That puts you on the harbor route, ie shortcut, follow till just past the town central where the vendor stalls are. Take a right which will take you past Sarafinas. At or near the end of the harbor area, bear to your right and you will pick up the road to Sandy Ground. Stay on the main road till you hit Cupecoy area. I would suggest that you do this only during daylite. Would not suggest this drive either way after dark.