FRSU,
Is the copy the same for each page on the front and back of the sheet? That is usually called 'step and repeat' imposition and yours would be 4up step and repeat. I created a quick layout to show you how to manually layout a 4up page in Scribus with guidelines and boxes for where the copy goes. I set it up as LETTER size with 4up layout, but it should give you the idea how to setup your page. I use Scribus 1.5.6, you will need this version to open and view.
Cheers!
mnawij