Digital BW, The Print

Question specific to loading paper through the back of the Epson 3000.

I'm trying to load Arches Hot Press (AHP) through the back and 
haven't figured out where to align it for proper centering on the 
page when printed.

Clues?

Thanks (in advance of course).
email direct if you like, either way.

Cleavis in AZ

PS. I was able to put AHP through the angle feeder in back but want 
to master the manual tractor feeder path since I will do a larger 
sheet at times.