A guide i found on the internet.
Here is How to Install iPhone/iPad simulator
First, you need to start a web app within WebMatrix’s UI. If you don’t have any apps running, you can get a quick start by picking existing application templates from the app gallery. Once you have an app running, like below, click on the Extensions icon.
Now this should bring up a new window where you should be easily find iPhone and iPad simulators.
Click install to complete installing the iPhone or iPad simulator. Once you are done, go back to the home windows of WebMatrix. Click on Run, from there you should be able to see a list of simulators you have previously installed. If you have installed iPhone or iPad simulator, it should show up there.
Click iPhone to launch the web app to a new iPhone simulator. But don’t worry the fun doesn’t stop here. Once you have the simulator open, you can pin it to your task bar, so next time you don’t need to have a WebMatrix window open to get access to the simulator.
As you can see, it’s a fully functional stand alone iPhone simulator (safari only).
One thing it lacks is the ability to rotate landscape view. I have yet to find a way to make this simulator to display in landscape mode. Perhaps it’s something they can improve on in the near future.
There you have it, a fully functional iPhone simulator via Microsoft.