Honestly... You're getting more into page-layout than document creation. Word does a better job of doing document creation than it does with page layout. Publisher is much better at page-layouts. You can accomplish the same task in Word... but it appears slightly different than you would expect.
Under the "Page Layout" tab... go to Margins -> Custom Margins (at the bottom of the list), and then near the middle of the dialog, there should be a "Multiple Pages:" drop-down-box with "2 Pages per sheet". Also set the page-layout to Landscape. On the screen while editing, it would appear like you're working on 1 skinny page... and as you add content... what appears to be the 2nd page will actually be printed on the second half on the 1st printed-page.