I am Howard C. Shaw III on Google+ - if you are on there, beep me, and I can do a Hangout and show you on my screen the steps and help you figure out why it is not working.
However, the basic and most critical thing for handling the Inkscape-
gt;OpenSCAD path is ensuring that you are exporting a path, as opposed to a different object type, and that it is solely composed of straight line segments.
The first item is managed by either performing an Object to Path or Stroke to Path from the Path menu. The second is managed by using the Edit paths by nodes (F2) tool, clicking the path, pressing Ctrl-A to select all, clicking the 'Insert new nodes into selected paths' 0..N times, then pressing t
he 'Make selected segments lines' button.
Basically, you can go ahead and press the segments-
gt;lines button, see if your result is too blocky - if not, you are done, if so, press Ctrl-Z (undo), Ctrl-A (select all), hit the + nodes button, then repeat the process until you are satisfied. Note that each repeat makes the result more complex and slower to render in OpenSCAD - it is basically the equivalent of the $fn= setting in OpenSCAD.
Finally - this whole sequence MUST be the last thing you do (aside from saving) before doing an export to DXF. Almost anything else you do in Inkscape will have a fair chance of re-introducing curves (i.e. scaling, inset, outset, etc) in which case you will have to repeat the process.
can have a look at http://www.thingiverse.com/thing:25036http://www.thingiverse.com/thi... - I haven't tried it yet, but it is apparently an attempt to get around the issue of going from Inkscape to OpenSCAD without having to do this sort of extra clean-up first.