Canon BJ-230 - Manual (Page 41)

If you select User Defined Size, the Setup program displays the
following dialog box:
First select the unit of measurement you are using (inches or
millimeters), and then specify the width and length of your paper.
T Click on the arrow next to the Paper Source setting to select one
of the followin paper sources:
Auto Sheet Feeder, which is the default
Manual Feed
NOTE: When you load letter-wide paper in landscape orientation, the
printer actually prints in portrait mode. So make sure you select
portrait for your printing orientation in the printer driver.
NOTE: When using manual feed, make sure the Print Manager is
turned off, in the Printers dialog box.