use standard 8 x 11 sheet
print both sides with pages in correct order
In the print dialog, select Brochure, select Print on both sides (duplex short edge), it should set the orientation to Landscape but check anyway.
Help on Printing a Brochure
Note that this will reduce font size to 71% of original so 12 point becomes 8.4 point. Consider your readership and whether you need to increase font size to allow for reduction