I heard about this a long time ago, and I tried goofing around with it. And I succeeded! I think it came out looking pretty nice. Here are some photos of it.
And here is how to make your own.
1: Make a wall that's width of the size of the staircase you want. Add some flooring on top.
2: Go to terrain tools.
3: Go to medium square brush, drag the brush softness to the bottom.
4: Click the spot where you want the "landing" to be 3 times.
5: Drag a foundation from the highest point (make it the size that you want your landing.) Make sure that the foundation is 2 squares away from the wall.
6: Level ground around foundation.
7: Place stairs.
8: Delete excess foundation.
9: Enjoy the functional staircase!
Okay, I looked this over and I think I made the tutorial understandable. If you have trouble, ask! I hope you enjoy