I just discovered that even if I use the Somfy 2 button controller driver, Webcore can see that button 3 (the home button) is pressed, so I can use a Webcore piston to automate actions based on press (or hold-release) of the home button, in addition to using the up and down buttons! Don't know if the Rule Machine can see it or not because I haven't used the Rule Machine, but the built-in button controller could not see button 3.
This applies to the Somfy Plus remote (also branded as a Bali Plus Remote).