Hi carpenterbee,
To run the completed application you click the Install button on the Arduino Firmata Tester Silverlight application on this page: YuleBlinker.com is for sale | HugeDomains . You install it directly from the web page. 'Installing' it means creating a local copy of the application that will run with elevated trust on your own computer - this is what Out-of_Browser means. An applicaiton running within the browser is 'sandboxed' and unable to communicate with local devices due to security restrictions.
You will be prompted with an install window, simply click the install button. The application will then usually place a shortcut on your desktop. If you have installed and configured Serial Proxy correctly, chosen the correct ports and set the correct baud rate then you'll be good to go.
I'm not too sure what you mean by... "A simple way to create the file to unsandbox your project/program would be nice.". Could you give a little more detail and I'll try to help out.
When working with the project in Visual Studio the option to 'Enable running application out of the browser' is found in the Project Properties page. Project > AndrewCraigie Properties... You will also find an Out-of-Browser Settings... button here too.
Hope this helps.
Andrew.