1.  Using Expression Encoder, encode your content and use Encoder to create a Silverlight player for you.  You can open that project file associated with the output and modify in Blend.  See Tim Heuer's blog post on using Expression Encoder templates as the foundation for your own Silverlight player.  If you don't have Expression Encoder, that is fine, but I have based my solution on some of the files it spits out.  If you are building your own player from scratch, you should be able to figure out what you need to do since Expression Encoder uses some of the same files that are provided as part of the Silverlight SDK (that I assume you are using or else you are one sick javascript writing puppy).

2.  Now we need to modify the default output of our Silverlight project to access content directly from the Silverlight Streaming service.  Step one is to change where our silverlight.js file is being downloaded from. 

a) Open default.html

b) Find <script type='text/javascript' src="Silverlight.js" mce_src="Silverlight.js"></script> and change it to <script type='text/javascript' src="http://agappdom.net/h/Silverlight.js"></script>.  This downloads a version of the silverlight.js file that allows us to instantiate our Silverlight object with a different method that we can configure to access content from Silverlight Streaming instead of a normal URL.

3. Next up, we need to update out startplayer.js file.  The first thing we want to look at is function StartPlayer_0(parentId).  It originally looks like this

function StartPlayer_0(parentId) {
    this._hostname = EePlayer.Player._getUniqueName("xamlHost");
    Silverlight.createObjectEx( {   source: 'player.xaml',
                                        parentElement: $get(parentId ||"divPlayer_0"),
                                        id:this._hostname,
                                        properties:{ width:'100%', height:'100%', version:'1.0', background:document.body.style.backgroundColor, isWindowless:'false' },
                                        events:{ onLoad:Function.createDelegate(this, this._handleLoad) } } );
    this._currentMediainfo = 0;     
}

as you can see, this function creates our Silverlight host by using the createObjectEx function.  For our purposes, we like this method of invocation because it allows us to specify what XAML we wanted hosted.  That way, even if the original content on Silverlight Streaming included it's own Silverlight player interface, we can use our own instead.  Unfortunately, createdObjectEx does not let us do this.  That is why we are using the other silverlight.js file, which allows us to modify our code as shown below:

function StartPlayer_0(parentId) {
    this._hostname = EePlayer.Player._getUniqueName("xamlHost");
    Silverlight.createHostedObjectEx( {   source: 'player.xaml?v=1',
                                        parentElement: $get(parentId ||"divPlayer_0"),
                                        id:this._hostname,
                                        properties:{ width:'100%', height:'100%', version:'1.0', background:document.body.style.backgroundColor, isWindowless:'false' },
                                        events:{ onLoad:Function.createDelegate(this, this._handleLoad) },
                                        initParams: 'streaming:/<silverlightAccountId>/<silverlightApplicationName>/somefile.wmv' } );

    this._currentMediainfo = 0;     
}

We change createObjectEx to createHostedObjectEx.  This allows us to still use our own XAML put also specify where the content comes from using initParam and the special syntax of stream:/...  Note that there is only a single forward slash following the colon, not two like in http://.  Following streaming:/ we put a Silverlight account number, followed by the application id that contains the content we want to get, and end with the physical file name of the media file.

4.  The last part is the part that was hard to figure out. If you are just hacking through the code like I was, it takes a little bit of time to figure out what needs to be fixed next.  If you look at the code inside of StartPlayer_0.prototype  you will see it ends with this._playNextVideo(); The code inside of _playNextVideo() function then calls the following function:

function get_mediainfo(mediainfoIndex) {
    switch (mediainfoIndex) {       

        case 0:
            return  { "mediaUrl": "somefile.wmv",
                      "placeholderImage": "someimage.jpg",
                      "chapters": [              
                                  ] };                                                               
        default:
             throw Error.invalidOperation("No such mediainfo");
     }
}

The issue is with the "mediaUrl" value.  By default, it points to the media file that Expression Encoder expects to be in the same web directory as the Silverlight player.  In our case, however, our content is actually in the Silverlight Streaming cloud.  It would seem that all you would have to do is change somefile.wmv to streaming:/<silverlightAccountId>/<silverlightApplicationName>/<somefile.wmv> and you would be good to go.  Unfortunately, life is not that easy.  streaming:/ is a place holder that the createHostedObjectEx function translates into an actual URL that points to the physical file in the Silverlight Streaming cloud.  That URL can be different each time you use streaming:/ even though you may be requesting the same file. 

There may be other ways to do this, and I suspect there are, but, I haven't taken the time to bone up on my javascript or the javascript libraries used by Silverlight, so I "brute forced" an answer based on some info I found on the web.  To fix the problem, I replaced the this._playNextVideo();  with a call to my own function this.loadStreamingVideo();.  The code for this function is added to the StartPlayer_0.prototype and is shown below:

_loadStreamingVideo: function() {
        var params = $get(this._hostname).InitParams;
        this._player.set_mediainfo(
            {"mediaUrl": params, "placeholderImage": "", "chapters": [] }
            );   
    }