There isn't a way to do it with loft right now, but it can be done with sweep as a workaround right now.

In the attached example, I created 2 rail curves along the top and bottom by using Draw curve / Freeform / Through points. Then select the 4 profile curves, and do a sweep with those 2 rails.

The resulting shape has a couple of shading glitches - you can fix these by going to Options and turning on "Add detail to inflections". I'm hoping to make this on by default after I have a chance to tune up the meshing a bit.

- Michael