For all configuration parameters in a model, you can right-click them and select "What's This?" This will bring up a small window which contains a table showing you the command-line way to use that particular parameter.
Following the above workflow, the parameters you care about are LoadInitialState and InitialState
You can do this either by using set_param before running the model or in the sim command itself.
>> set_param(bdroot,'LoadInitialState','on','InitialState','variableName');
>> simout = sim(bdroot,'StopTime','10');
>> simout = sim(bdroot,'StopTime','10','LoadInitialState','on','InitialState','variableName');
- Sebastian
