Оказывается всё просто =)

const kMyFlag = app.stringIDToTypeID( "myFlag" );
const kMyNumber = app.stringIDToTypeID( "myNumber" );
const kMySettings = "mySettings";

function saveSettings()
{
var desc = new ActionDescriptor();
desc.putBoolean(kMyFlag, true);
desc.putInteger(kMyNumber, 42);
app.putCustomOptions( kMySettings, desc, true );
}

function getSettings()
{
var desc = app.getCustomOptions( kMySettings );
return [desc.getBoolean( kMyFlag ), desc.getInteger( kMyNumber )];
}