Step 1) Face the wall with your character and line them up near the gray, vertical marking on the wall. Be sure your character is touching the wall. For those of you that can't tell, it's on the left side of the SW bank when you walk in. You can probably do it on the right side too, but this is how I did it.
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Step 2) Kinda tricky if it's your first time. It's pretty simple though, just jump and press the E key or D key (I'm assuming both motions will work , I just used the E key). If you can't get near the point in the picture, try pressing the E key very soon after tapping the space bar. This seems to help.
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Step 3) Do the same thing as step 2. Tapping the space bar and hitting the E key quickly after may also help once again.
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Step 4) At this point, I usually rotate the camera a little bit by holding down the right mouse button and moving the mouse to the right, just to line up the next jump a little better.
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Step 5) This is the final jump. To me, it seemed that unlike the previous jumps, you do not want to tap the space bar and tap the E key soon after. Rather, wait a bit longer before hitting the E key (about at the peak of your jump). You should end up on top of the ledge.
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Enjoy taunting people on the ledge and the constant howd you get there!