You can create a new imposition schema to meet your needs. To do so, take a look at the imposition definitions stored in <code>page-imp.mkiv</code> and find the closest one to work with. You can access the file online:
https://source.contextgarden.net/tex/context/base/mkiv/page-imp.mkiv?search=%5Cinstallpagearrangementinstallpagearrangement
Let's say we want this page arrangement on one sheet (R = page upside down):