It sounds like you will have eight sheets in each part. Each sheet holding four pages (two front, two back). These eight sheets will be bound together. In English, such a collection of folded and bound sheets is called a signature. So we are talking about 8 sheet signatures.
PDFClerk can do this in one go:
1. Set the 2-up imposition (“2-pages per sheet side”)
2. In the toolbar set the “Signature Sheets” to 8. (As soon as you’ve done the this you will see that page 32 is placed next to page 1 on the imposition.)
The PDF is now ready for printing.
If you need to deliver 6 PDFs, a separate one for each signature then use the Export->Explode feature from the File menu:
1. Bring up the Explode Dialog
2. In “Sheets Per Document” fill in 16 (this should read “Sheet Sides Per Document” and will be corrected in the next update), since 16 sheet sides is 8 sheets, which constitutes one signature.
3. Change source name and first file name options if appropriate and click “Explode”.
You now have 6 PDFs, one each per signature.