Hi im new to this site and just wanted to contribute, so here is my guide to get under SW.
1. Just before the exit to the bridge between Trade district and MAge quater there is a wall, face it.Image 1 Image 2
2. You should notice there is a slight change in texture like a line running down the wall. At any point from the right of that line to the lamp run at the wall and jump till you are standing in mid air. Image 3
3.Next turn to the right and aim your self at the lamp. Hit space and forward really hard and try to land on the lamp like this.This can be really tricky so don't be worried if you dont get it on the first go. Image 4
4. Now Turn so you are facing the little ledge above you and again hit forward and space really hard. This can also be reall tricky but you should try to land on the ledge like this. Image 5
5.Now just run forward till you find yourself going through the wall and under SW. Image 6
I hope you enjoy this and if it's been posted before im sorry i cant search cuz im a 'leecher' so don't flame thank you!!!