S3Express is very easy to install and it will work out of the box.
Just download one the installers (32-bit or 64-bit) and then run the installer. S3Express will be installed in its own folder, under "Program Files", unless otherwise specified. Then click on the S3Express icon to start the command line utility. That's it! The entire installation is less than 8MB in size.
S3Express is a self-contained program. It's compatible with all Windows versions, including Windows Servers. It does not require any additional libraries or software to run.
S3Express does not modify any general Windows settings or any other program settings. It does not install any Windows services or Windows drivers. It can be cleanly uninstalled if needed (instructions), without leaving any traces, and by default it runs without administrative privileges (non-admin).
The S3Express installer and the S3Express.exe executable are digitally signed by TGRMN Software.