unfortunately, there is no scripted action built inside XSI, not that we users really miss it. its just matter of creating camera, setting the co-ordinates and setting it to Orthographic view instead of perspective ....
may be it can be changed to your requirements. Now!! this is cool since you just need to do this once... save it as a script and integrate it inside the GUI. next time when you do want to use the "back View" all you may need to do is.. click a button or type in your keyboard shortcut....