I don't beleive I have ever seen a torque spec on the studs, just as with any stud on a bike.
This should tell you to apply thread locker sealant to the stud, and install it snugly, but do not over torque it. The stud binds tight when the thread bottoms out, over toquing may cause the surrounding boss to crack. The torque induced on the stud's body linearly when the bolthead is drawn up on it with the springs in position should be followed though.