How can I add an input to a Stateflow chart?

I've been using the Stateflow library, but I can't create an input to a chart with the API.

sfnew('MyChart');
root = sfroot;
blockDiagram = root.find('-isa','Simulink.BlockDiagram');
chart2 = blockDiagram.find('-isa','Stateflow.Chart');

How can I add an input to the chart? I've tried the add_param function but without success...

Thanks

[João]

I managed to do something about my question:

% Initialization
sfnew('MyChart');
root = sfroot;
blockDiagram = root.find('-isa','Simulink.BlockDiagram');
chart = blockDiagram.find('-isa','Stateflow.Chart');
chart.Name = 'Connector';
%chart.Position = [40 40 100 60];
input = Stateflow.Data(chart);
input.Scope = 'INPUT_DATA';
input.Name = 'LuxLevel';
output = Stateflow.Data(chart);
output.Scope = 'OUTPUT_DATA';
output.Name = 'State';

With this, it is possible to set variable to input and output.

I've another question: how can I insert a Light Bulb block by code?

For a Manual Switch I can do this:

switch1 = add_block('Simulink/Signal Routing/Manual Switch','MyChart/sw');

For a Light Bulb I don't know how can I do it, since I can't use this for example:

add_block('Gauges Blockset/Global Majic ActiveX Library/On Off Gauges/Light Bulb','MyChart/Light');