Hi, did you ever get it to work? I have the same problem. Here's the thread that I just created somewhere else on this site -
I have a photosmart c4280 and a Mac OSX 10.4.11.
The 2-sided printing feature doesn't work for both Word and pdfs.
I go to 'print', 'layout', and then try things like 'pages per sheet' - but the "two sided" button is always in a lighter shade, and it doesn't allow me to click on it.
Does anyone have advice on how to fix this? It'd save lots of trees and money to print double sided. Thanks!