|G Wall (aka H Face)
Slingshot is harder than Boardwalk and Little Inch because it requires some smearing at points, especially near the bottom. But there are also some ledges an inch or two in width which make the climb relatively easy, higher up.
Slingshot starts between Boardwalk and Little Inch on G Wall. It isn't perfectly well defined, but Boardwalk and Little Inch both start along cracks. Climb up the face between them to do Slingshot.
This route is listed in the Boston Rocks guide, but the end is not described. Heading for an anchor somewhere near the end of Little Inch or Boardwalk is my guess.
The top rope set up is similar to that for Little Inch or Boardwalk. Head past H Wall using the stone path. Take the obvious trail to the left, and go left to reach the peak. There are two trees and two giant, old, but sturdy, metal staples at the top which can be used to anchor (about 50 feet of slings should be plenty). Make sure your rope is not running over the sharp edges of rock near the top!