Open the document. Then go to the Print dialog box. There is a little checked box that says "Auto Rotate and Center" - Uncheck that box.

Then hit print, and it will print the left half of the document.

Then under the View menu, hit the "rotate document" selection and choose "Rotate Clockwise." Do that again, so now the page is upside down, but that's okay! Now when you hit print, it will print what used to be the right side of the document.

Got it?