Download the distributive file and save it on your hard drive. Run one of the command lines below.
To silently install the free version of 2TIFF:
2tiff-free-setup.exe /SILENT
To silently install the commercial version of 2TIFF (using a serial number):
2tiff90-commerc-setup.exe /SILENT /SN=BBBBBB-AAAAAA-DDDDDD-CCCCCC