Accessing ScriptManager proxies in code

I have a situation where I'd like to add a "last modified" timestamp to the paths of my js files (ex. "custom.js?2009082020091417") that are referenced in my ScriptManager (contained in my MasterPage) and in any ScriptManagerProxies (content pages).

I can easily get access to the ScriptManager in code and then iterate through it's Scripts collection to get the Script paths that I've set declaratively and then "set" a new path with the tacked on "?[lastmodifiedtimestamp]".

The problem is, I can't figure out how to get to any ScriptManagerProxies that may exist.

When debugging, I can see the proxies in the non-public members (._proxies). I've looked through the documentation and can't see where you can actually publicly access this collection.

Am I'm missing something?

I have the following code in the base class of my content page's Page_PreRenderComplete event:

ScriptManager sm = ScriptManager.GetCurrent((Page)this);
if(sm != null)
{
     foreach (ScriptReference sr in sm.Scripts)
     {
         string fullpath = Server.MapPath(sr.Path);
         sr.PathWithVersion(fullpath); //extension method that sets "new" script path
     }
}

The above code gives me the one script I have defined in my MasterPage, but not the two other scripts I have defined in the ScriptManagerProxy of my content page.

Came up with a solution. Seems that the only place that all the merged scripts can be accessed is in the main ScriptManager's ResolveScriptReference event. In this event, for each script that has a defined path, I use an extension method that will tack on a "version number" based on the js file's last modified date. Now that my js files are "versioned", when I make a change to a js file, the browser will not cache an older version.

Master Page Code:

 protected void scriptManager_ResolveScriptReference(object sender, ScriptReferenceEventArgs e)
 {
    if (!String.IsNullOrEmpty(e.Script.Path))
    {
        e.AddVersionToScriptPath(Server.MapPath(e.Script.Path));
    }
 }

Extension Method:

 public static void AddVersionToScriptPath(this ScriptReferenceEventArgs scrArg, string fullpath)
 {
       string scriptpath = scrArg.Script.Path;

       if (File.Exists(fullpath))
       {
           FileInfo fi = new FileInfo(fullpath);
           scriptpath += "?" + fi.LastWriteTime.ToString("yyyyMMddhhmm");
       }

       scrArg.Script.Path = scriptpath;
 }