With this extension you can start/stop your SFX100 with any button from any controller in SimFeedback. You can also change the overall intensity on fly with configurable buttons in increments of 1%, 5%, 10% and 20%.
Download (or clone) this github project.
Copy the folder 'ButtonBoxExtension' inside the 'extensions' folder in the SimFeedback root folder.
Run remove_blocking.bat.
Start SimFeedback, go to the setup tab and tick the activated and autostart checkboxes for this extension.
Go to the extensions tab.
Click Refresh Joysticks, and select your controller.