Quote - ... I want this morph to be set to 'on' at all times...

In the relevant targetGeom channel:

                        forceLimits 1
                        min 1
                        max 1

"forceLimits 1" tells Poser to respect the limits set in the two lines below. "min" and "max" are the actual minimum and maximum values the channel is allowed to have. "initValue" is the value that the channel will be set to when you use the Restore command, but this will not override forced limits, and so is not relevant in this case.