See http://www.thingiverse.com/thing:14221

Installation

Simply copy the appropriate files (openscad_dxf.inx and the openscad_dxf folder) to the installation directory. Install to your Inkscape global installation's extensions directory or to your local user's inkscape extensions directory. The per platform installation directories can be found below. If you have pip and want to try an even easier (but experimental) installation method you can try using pip install --target=<installation_dir> inkscape-openscad-dxf. If you do use this method, do not use a ~ to refer to your home directory. Some versions of pip will misinterpret it and create a directory called ~ in the current directory.

Windows

• Global - C:\Program Files\Inkscape\share\extensions
• Local - C:\Documents and Settings\User\Application Data\Inkscape\extensions

Linux

• Global - /usr/share/inkscape/extensions
• Local - $HOME/.config/inkscape/extensions

OS X

• Global - /Applications/Inkscape.app/Contents/Resources/extensions
• Local - $HOME/.config/inkscape/extensions