In order to get it to print on one sheet of paper, I put the margins of my printer page in my Netscape browser to "zero" inches on all sides. (File - PageSetup - then set the margin size.) I have a HP printer which will still add a margin, but this way it all stayed on one piece of letter size paper.
If you can't get it to print on one "letter size" sheet, try setting your printer to "legal size" paper and put in legal size paper and that should work to keep the pattern in one piece of paper and not split at the bottom onto another sheet.
This is a larger file than most and will take a little more time to print.
You will need to trim one the center area of the pattern on the dashed line, and leave a little tab of paper beyond the dashed line on the other half so you can glue the two pieces together. Think of the "tab" as a seam allowance.
Let me know if it works for you!