Not a direct answer, but most blueprint shops these days have at least one wide format printer. It's pretty cheap to send to them and have it delivered.
However, if you must print on letter size sheets......I don't know if AdobeReader has this option but the full AdobeAcrobat does, when you go to print and the dialog comes up, under the Page Handling section you can select Tile Large Pages. It will even place crop marks for easy lining up later.