Currently we do not have the ability to render horizontal facet chart.
The one option would be to use CSS transformations to rotate the chart. The main big problem with this is that not all browsers support pointer capture - for example on Chrome the interactions break once you drag the mouse pointer outside the chart area (while on IE11 it works correctly).
http://jsfiddle.net/8gveybed/
#demo {
width: 500px;
height: 500px;
transform: rotate(90deg);
transform-origin: middle left;
}