You can use the .exe file in the bin\Debug folder.
-usage
Print the usage information.
-split
Please use "PDFSplitMerge.exe -split [SourceFile] [Pages] [OutputFolder]", DO NOT contain any space in [Pages].
For example:
PDFSplitMerge.exe -split c:\Users\foo\Desktop\bar.pdf 1,2,3-4 c:\Users\foo\Desktop\
-merge
Please use "PDFSplitMerge.exe -merge [File1] [File2] ... [FileN] [OutputFolder]"
For example:
PDFSplitMerge.exe -merge c:\Users\foo\Desktop\bar.pdf c:\Users\foo\Desktop\bar2.pdf c:\Users\foo\Desktop\
iTextSharp.dll can be downloaded here http://sourceforge.net/projects/itextsharp/