>Whenever i try to insert a field "PRINT 27 &l1S" into my Word document to get duplex on in the document, i get a message from word stating that the printerdriver does not support the print command. (the exact message is in dutch, i will spare you the words).
>
>does this sound familiar to anyone and/or does anyone have an alternative to get duplex on, on a document by document basis ? (changing the printer driver properties is not quite an option here.)

It's printer level setting so you don't have much choice. See if http://support.microsoft.com/kb/828638 and http://pubs.logicalexpressions.com/Pub0009/LPMArticle.asp?ID=116 could give you some pointers.