简短的回答是，这是不可能做到的，但是Cassini源代码揭示了一个替代解决方案。

• • 更新**

上面的链接不再起作用，但是CodePlex上的CassiniDev project看起来非常接近（可能是衍生作品），并且包含相同的解决方案。
解决方案是避免使用CreateApplicationHost，而是"自己动手"-在本例中，使用反射创建内部"BuildManagerHost"类型的示例并调用"RegisterAssembly"，如下所示

/// <remarks>
/// This is Dmitry's hack to enable running outside of GAC.
/// There are some errors being thrown when running in proc
/// </remarks>
private object CreateWorkerAppDomainWithHost(string virtualPath, string physicalPath, Type hostType,int port)
{
    // create BuildManagerHost in the worker app domain
    //ApplicationManager appManager = ApplicationManager.GetApplicationManager();
    Type buildManagerHostType = typeof(HttpRuntime).Assembly.GetType("System.Web.Compilation.BuildManagerHost");
    IRegisteredObject buildManagerHost = ApplicationManager.CreateObject(_appId, buildManagerHostType, virtualPath,
                                                                  physicalPath, false);
    
    // call BuildManagerHost.RegisterAssembly to make Host type loadable in the worker app domain
    buildManagerHostType.InvokeMember("RegisterAssembly",
                                      BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic,
                                      null,
                                      buildManagerHost,
                                      new object[] { hostType.Assembly.FullName, hostType.Assembly.Location });
    
    // create Host in the worker app domain
    // FIXME: getting FileLoadException Could not load file or assembly 'WebDev.WebServer20, Version=4.0.1.6, Culture=neutral, PublicKeyToken=f7f6e0b4240c7c27' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418)
    // when running dnoa 3.4 samples - webdev is registering trust somewhere that we are not
    return ApplicationManager.CreateObject(_appId, hostType, virtualPath, physicalPath, false);
}