How to Make Your Model Defy Gravity.

Strong calf muscles and great balance is what it takes to pull off a pose like this. Just kidding.

This shot is fairly simple to do. The most important component for this shot is to use a tripod. In my case I could not shoot at this location with a tripod since it was simply not allowed.  First you setup the composition you are looking for without the model in place. Then set your camera to manual since you don't want the metering to change once the model is introduced.  Meter for the scene (I prefer using matrix metering in these situations).  Also make sure your white balance mode is fixed. Once all the variables have been locked take a shot of the scene without the model as shown below.

After your satisfied with the shot introduce the model with a helper (in this case her husband). Have the model lean gracefully on to the helpers hands, in this case I forgot to have the helper adjust his hands so I ended up cloning them out later. Once the model is in a satisfactory pose take the shot. 

Now, in Photoshop open both the shots, and have the shot without the model (A) placed below the model shot (B). In shot B open a mask layer and with a black brush mask out the helper so only the stairs/background is visible. And that's it viola.