The installer supports an answer file named sinstall_values.ini. The syntax is explained within the setup dialog.
Contents for version 5.5.2 could be:
INSTALL_DIR=C:\Program Files\Quest Software\SQL Navigator 5.5.2
The resulting cmd line is
The Toad Data Modeler Free Edition installer is placed in the program directory and can be called later on from that location. (Setup_TDM_Free.exe, Inno setup with usual /LOADINF /SAVEINF switch support)