simplest way:
-make a mark on your material (manually with a sharpee) with a reference point on your printer, where your material start is.
-print centered
-feed extra before cutting, so that you have material for your printer to feed
-flip and use marks you made to re-align your page to print 2nd side
(make sure you flip the file in the rip, as well, to make sure you're printing the right way)