Thanks
, that worked, but is by no means self explanatory.
One would think that as long as the S2 switch appears as an individual device, one could set up a trigger based on its state.
This actually works to some extent, but it requires that the S2 switch is toggeled in Indigo. The push of the actual physical switch does noe change its state in Indigo, and it registeres as a device change to the dimmer itself.
So scenes is the only way to make this work.
After realising this I had no problems setting up the S2 switch to control the off and on stat of hue lights.