1. From the application's menu, click File
2. Click Print
3. From the Printer drop down, locate and click the desired printer
4. From the Presets drop down, locate and click Layout. This will change what settings are available
   
5. From the Two-Sided drop down, locate and click Long-Edge binding
   
6. From the Presets drop down, locate and click Save Current Setting as Preset...
   
7. Type the desired name to identify the preset (e.g. Duplex).  Click the radio button for All printers.
   
8. Click OK

When you would like to print duplex, simply choose the printer and then select the preset that was created.