You can apply your facing around any shape at all. It doesn't have to be the same on the sides as it is on top/bottom. Follow the directions in the link I sent yesterday when you asked this question. The facing on the top/bottom will need to be wider than the facing on the sides since the measurement between the innermost and outermost points is larger.
Here's an example of one. It's an antique quilt and doesn't say whether it's faced or not, but you can see the edges were preserved.
http://www.johngouldantiques.com/cmp...?g2_itemId=347