Run the Exe to msi Conveter and click 'New MSI Package'. The Project Wizard is started.
Selct the Firefox executable installer file "Firefox Setup.exe".
Exe to msi converter detects the installer type as 7-zip self extracting archive.
Click Next and choose "Silent installation with command line parameters" conversion method.
The silent install parameters for the Firefox installer can be found on official mozilla site: wiki.mozilla.org/Installer:Command_Line_Arguments
Silent install parameter: -ms
Silent uninstall parameter: /S
Click Next and finish the Project Wizard. New project appears in the Projects tree.
Now you can build the project.
The Build Dialog opened. Click 'Build Package' button.
The Firefox MSI package will be created.