Obtain the Multivalent PDF Tools (
http://multivalent.sourceforge.net/Tools/index.html)
You can change a PDF's page size using:
java -cp multi.jar tool.pdf.Impose -dim 1x1 -paper 5.24x6.69in input.pdf
Multivalent also comes with a very useful PDF splitting and page deletion tool:
java -cp multi.jar tool.pdf.Split -page 2,4-end input.pdf (this deletes pages 1 and 3)
As for cropping, you may want to evaluate the the pdcrop/pdcat tool.
pdcrop.exe -nb MediaBox -shrink 80:60:-297:-421 input.pdf output.pdf
The pdcat tool can also set the MediaBox and CropBox using the following commands:
pdcat -box
pdcat -crop
Regards,
Mosh