Step 2: Setting up Inkscape and "Better DXF Output"
To install the "Better DXF Output" extension, download the file better_dxf_output.zip. Extract the three files and put them in "C:\Program Files\Inkscape\share\extensions" (if you installed the Windows version) or "...\InkscapePortable\App\Inkscape\share\extensions" (if you're using the Windows portable version) or "usr/share/inkscape/extensions" (if you installed the Linux version).
Start up Inkscape and you should now be able to save drawings as "Better DXF Output" files. We need to use this extension because OpenSCAD requires R12 DXF files, and Inkscape 0.48 and newer exports R13 DXF files.