The installer supports Inno Setup based installers standard command line parameters, and also the following that are specific to the PDF-ShellTools setup functionality.

/handlers=

Used to specify what Shell extensions to register. Sequence of a R to register, or U to unregister, for each of the Shell extension handlers available to the Windows version where it is being installed.
For pre-Windows Vista the Shell extensions are: InfoTip, InfoEdit, Context Menu Tools, Insert/Append/Attach on drop and Column Handler.
For Windows Vista, and up: InfoTip, InfoEdit, Context Menu Tools, Insert/Append/Attach on drop, Property Handler and Preview Handler Tools.
Example: In a Windows 8.x, a /handlers=RURRRR will register all the Shell extension handlers, except the InfoEdit.