I have wanted to be able to manually print duplex for sometime but never scratched the itch until today. With a quick Google search and I discovered
http://www.maclovin.de/2009/03/manual-duplex-printing-with-osx-presets/The basic plan is to print the document twice. The first print prints only the odd pages. The second print prints only the even pages and (very importantly) with a reverse page orientation. So, print the document using the first settings. Next, take the stack of pages from the output tray and place them in the input tray as is, that is, don't flip them or turn them in anyway. Lastly, print the again document using the second settings. The result is a duplex document with the pages in the correct order in the output tray.
Max OS X allows for creating printing presets and so I have created a "Duplex Pass 1" and a "Duplex Pass 2" presets. The only bug is that the "Reverse page orientation" setting (aka checkbox) seems to be independent of the preset so be sure to make sure it is unchecked for pass 1 and checked for pass 2.
HP has a very useful application for manual, duplex printing but it has stopped working since OS X 10.8.4.