The silent installation of the two required products is non-standard, and not immediately obvious.

1) Silently install Ghostscript

Using v8.15 from Cute PDF
http://www.cutepdf.com/download/converter.exe

- Rename converter.exe to converter.zip
- Right click on converter.zip and select Extract All...
- Click Extract
- Run converter\Setup.exe

OR

Using 8.63 from SourceForge
http://downloads.sourceforge.net/ghostscript/gs863w32.exe

- Rename gs863w32.exe to gs863w32.zip
- Right click on gs863w32.zip and select Extract All...
- Click Extract
- Run gs863w32\setupgs.exe "%ProgramFiles%\gs"

Note: This may not work over a UNC path. Using pushd and popd as per http://www.appdeploy.com/packages/detail.asp?id=515 may resolve the issue (courtesy Andy Hawkesworth).

2) Silently install CutePDF Writer

http://www.cutepdf.com/download/CuteWriter.exe

- Run CuteWriter.exe /verysilent