There really isn't a matlab interface.
The code samples and that getting started were developed on an older version of matlab at the time which did not support event driven programming.
I imagine that event driven programming can be done in Matlab with Phidgets, as in Matlab you are only loading an external c library into your program. However this will depend on whether the Matlab connections to the library will be able to handle the events in the Phidgets c library.
We haven't had the opportunity to test this ourselves. I believe we are hoping to be able to move to a newer version of Matlab and test this out properly, but I am not sure when that will happen at this time.