Windows 7: HP 840c duplex

Hi all
I still have an old hp840c printer and I would like it to support duplex printing like it was in XP (now having 7 ult. x64). I've installed the windows driver like hp suggested in their site and the printer is working fine but there is no two-sided-printing anywhere in the configuration screens. Only office 2010 has a duplex printing of its own regardless of the driver but it's not enough for me. I need it to work with Acrobat and any other software.
I'll be happy to hear practical solutions for this issue (and not something like "do it manually").

Thanks