Printing booklet A6 format

With pdfbook2 it is possible to convert a pdf from A4 format to one which one can print onto A4 format, but then fold the pages in the middle and get a booklet of A5 format. I would like to go one step further, and reduce this to A6: Print on four pages onto one sheet of A4 paper, cut it in the middle, and then fold the resulting A5 paper to get a booklet of A6 size. pdfbook2 doesn't seem to have an option for this, running it twice does not produce the desired result, neither does printing the result with two pages per sheet of paper.