Create Puppet Pin on existing mesh via scripting

Does anyone know how to create a puppet pin via scripting?

When I do something like this :

var puppet_pin = puppet_layer.effect.property('ADBE FreePin3').property('ADBE FreePin3 ARAP Group').property('ADBE FreePin3 Mesh Group').property('ADBE FreePin3 Mesh Atom').property('ADBE FreePin3 PosPins').addProperty('ADBE FreePin3 PosPin Atom');

puppet_pin.property('ADBE FreePin3 PosPin Position').setValue([500,500]);

A pin is created but it is greyed out and does nothing.  I notice that the 'ADBE FreePin3 PosPin Atom' property contains two other properties, but they seem to be read-only.

Any way to get around this?

Thank you!