MIDI FX Scripts in MainStage: Initialize variables when patch becomes active?

I've got a MIDI FX script I use in MainStage that steps through a list of chords with a single note press (basically working around my limitations as a keyboard player). 

It works well, but I've found that it doesn't always start at the beginning of its list of chords because I didn't step all the way through the last time, or what have you.

Is there a way to initialize variables when a patch containing MIDI FX scripts become the "active" patch?  The script has a variable which basically acts as a pointer in the array, and I just want that variable to reset to 0 when the patch becomes active.

You could create a parameter in your script that sets that variable and assign a controller button to it. I don't know if that solution would suit your needs though. Pardon my ignorance, what do you mean by patch? A Channel strip preset? While I do own MainStage, I've fired it up maybe three times the whole time I've had it.  I mainly use Logic.

Just assign another note press to reset the counter and press both when you "start" the list?

You can setup an non-assigned mapping to [YOUR PATCH] > [YOUR CHANNEL STRIP] > MIDI Controller > [CC##].

Choose a Saved Value. i.e. 127.

This message can then be sent when changing to that Patch by using the On Patch Change:Reset Attribute.

Lastly reset your variable from that message.