How do I programmatically change data names in a Stateflow Chart

First you use the 'sfroot' function to get a handle to the root Simulink object:

>>rt = sfroot;

Then you use the 'find' method to get a handle to the chart:

>>ch = rt.find('-isa' , 'Stateflow.Chart')

Lastly, you use the 'find' method again to get a vector of the data objects:

>>signals = ch.find('-isa' , 'Stateflow.Data')

You can edit any property of the data object and Stateflow will automatically update. For instance, if you wanted to change the name of the first signal, you can execute:

>>signals(1).Name = "First_Signal"