I have a user that is printing on top of pre-printed forms on a Lexmark T642 and so the page alignment needs to be very exact so that the data they print lines up with the boxes.
Currently the form is printing about 3/4 of a character off to the right.
I have looked through the settings on the printer drivers for default margin/offset settings.
I also looked at trying to define a custom page size but in the definitions for the page size it only takes Width and Height, no control for the printable area.
Try printing a PDF that's the native paper size set to no zoom, you should be able to work out from there if the printer's actually offset, or just adding a margin.