Printing A4R from the manual tray on a HP Laserjet 5100

Dear all, Because of very often paper jams we like to insert our paper in the manual tray not starting with the long side, but with the short side. Of course we can do this, but then the text is not printed on the right place. We are working with Macs, Leopard 10.5.8. We cannot choose from Word the option papersize 4R, also we cannot choose the option 4R in the manual tray of our printer. We tried to make a custom size in Word, so we can choose in Word in Page Setup 4R. But then it still does not work. We think it is because the printer does not support this. Has anybody an idea what we can do? I am looking forward to hear from you! Dorothee