Hi,
I am not sure if this is possible. However John Brinkman has a sample of a form flowed from top to bottom, which anchors the total row at the bottom of the page. (http://blogs.adobe.com/formfeed/Samples/AnchorBottom.pdf).This required a spacer than reduced in height as more elements (rows) were added to the form.
I tried to use this for a particular application, but was not successful. In your case, you could possible set up a spacer as the first element in a form flowing from left to right. As more elements are added the spacer would get smaller thus giving the impression that the flow was from right to left.
Good luck,
Niall