From the FAQ:
Q: Is it possible to perform a silent installation of this software?
A: Starting the setup with the command line parameters /SILENT /PASSWORD=YourInstallPassword will perform a silent and automatic installation with the default settings. Please replace YourInstallPassword with the installation password that you received after your registration. Using /VERYSILENT instead of /SILENT will prevent any visual feedback. The option /DIR="x:\dirname" can be used to override the default install path.