Using ConTeXt (taken from the imposition explanation):
\definepapersize [filius][width=136mm, height=232mm] \setuppapersize [filius][A4,landscape] \setuparranging [2UP,doublesided] \setuplayout [backspace=0pt, topspace=0pt, width=middle, height=middle, location=middle, header=0pt, footer=0pt, grid=no, marking=off] \starttext \insertpages [document.pdf][width=0pt] \stoptext
You have to replace the document.pdf
with the real file name and filius
with the original paper size.