I can't even believe I'm asking this, because it's something I can
normally figure out in about 30 seconds with pencil and paper.

I am making a program for a school event.  It'll be a
landscape-oriented sheet of paper, printed on both sides, so that the
"back" is the front and back cover of the program, and the "front"
will be the inside pages.  Simple enough.

So I set up a two-column, single-row table on the paper, invisible
borders, to be the text.  Left column is the inside left of the
program, right column is the inside right of the program.  Also
simple.

Here's where my mind needlessly melts:

I set the document margins to 0.4 inches all the way around.  The
table cells have their content centered.  BUT... in the finished
product, it's NOT justified when printed.  Why not?  Well, on the left
side, the table begins 0.4 inches from the edge of the paper, then the
cell has a margin of 0.08".  The table center is the page center.  So
a line of text completely spanning that table cell will be 0.48 inches
from the left edge, but only 0.08" from the "right edge" (actually the
center of the single sheet of paper).

So... could someone tell me how to make the stuff appear centered for
what I'm doing?  I know there are a bunch of ways.  Certainly
jiggering the page margins, or the table position, or the cell
margins, or some combination.  Heck, maybe there's even an easier way
I don't know about (perhaps rigging it to print two pages per
sheet??).

I think my mind is fried, because this is really something I should
have solved myself, and a lot sooner than this!