Printing Directly to the Copier From Your Desktop
Turn on Duplex printing by checking the "Two-Sided box. Then Set "Pages per Sheet" to two (2). Finally make sure you are duplexing on the "short-edge".
One more interesting twist I just remembered. You can save the print job so that you don't have to keep sending it over and over to the copier. This is different than sending it to the Document Server (below).
In the "Job Log" window, just set "Job Type" to "Stored Print.