i'm not an expert on foosball terms so bare with me. to do the S curve with the center man on the three bar, trap the ball in the furthest back position (facing your goal) there are 2 ways you can go, use the dots to decide where to shoot. i usuall will acually let the ball go at the second dot fom the center.. you can either 1. shoot a sraigh masse curve around the defense and in or 2. try to bust the S which will weave out, then in then slightly out again just before it reaches the goalie.. for the S, you trap the ball direclty on top of the second dot pusch side of the center dot, have the ball on the push side of you man (about half way off the man and half way under) then move your bar to the push side just until the the ball is in the exact opposite position of where it was ( so it is 50 on 50 off the pulls side). then go directly back to where you started (50 on 50 off the push side 2nd dot) and release.. this should all be done in one fluid motion with TONS of pressure on the ball.. the ball has tons of spin and the first direction it goes is to the push side, that is because of the pressure from it being popped out, then the actuall spin comes in and brings it toward the goal and to the pull side, the final spin is very slight but i moves the ball about and inch to two inches to the push side, this is because of the way you "wind up" and the ball actually comes out on a wierd angle so it has alot of spin one way and it's a little off axis spining another, so when the 2 spin dies down it catches that last little spin from an off angle..
it also works very well as a fake because when you move it back to get force for the masse, you can also release with medium pruessure on your pulls side for a regualr masse in. Again i don't know if it's me or what but most of the people i play with cannot come with in a quater of the pressure and spin i can do without trying really hard..