I have been able to get some code from one of my colleagues and Extensibility support specialist, Ed Dore, that may help with the Toolbox control installation in Visual Studio 2005. I must remind you that the code that I post here comes with a Disclaimer.

In the code below you need to replace the following with your values:

<Path to the control dll>: Path to the dll that contains the toolbox control

<Toolbox Tabname>: Name of the Toolbox tab on which to add the controls.

HTH,

Chetan

using System;

using System.Collections.Generic;

using System.Text;

using System.Runtime.InteropServices;

using EnvDTE;

using EnvDTE80;

using System.IO;

namespace InstallToolboxControls
{
   

// Definition of the IMessageFilter interface which we need to implement and 

    // register with the CoRegisterMessageFilter API.

    [ComImport(), Guid("00000016-0000-0000-C000-000000000046"),
    
InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
    
interface IOleMessageFilter // Renamed to avoid confusion w/ System.Windows.Forms.IMessageFilter

    {
        [
PreserveSig]
       
int HandleInComingCall(int dwCallType, IntPtr hTaskCaller, int dwTickCount, IntPtr lpInterfaceInfo);
        [
PreserveSig]
        
int RetryRejectedCall(IntPtr hTaskCallee, int dwTickCount, int dwRejectType);
        [
PreserveSig]
        
int MessagePending(IntPtr hTaskCallee, int dwTickCount, int dwPendingType);
    }
 



    class Program : IOleMessageFilter

    {
        [
DllImport("ole32.dll")]
        
private static extern int CoRegisterMessageFilter(IOleMessageFilter newFilter, out IOleMessageFilter oldFilter);
       
 static string ctrlPath = <Path to the control dll>;
        [
STAThread]
        
static void Main(string[] args)
        {
            

Program program = new Program();
            program.Register();
            

if (args[0].Equals("-Install", StringComparison.CurrentCultureIgnoreCase))
                program.InstallControl();
            

else if (args[0].Equals("-UnInstall", StringComparison.CurrentCultureIgnoreCase))
                program.UninstallControl();
            program.Revoke();
            


// to ensure the dte object is actually released, and the devenv.exe process terminates.

            GC.Collect();
            
GC.WaitForPendingFinalizers();
        }
        

void InstallControl()
        {
            

// Create an instance of the VS IDE,

            Type type = System.Type.GetTypeFromProgID("VisualStudio.DTE.8.0");
            
DTE dte = (DTE)System.Activator.CreateInstance(type, true);
 
            

// create a temporary winform project;

            string tmpFile = Path.GetFileNameWithoutExtension(Path.GetTempFileName());
            
string tmpDir = string.Format("{0}{1}",Path.GetTempPath(),tmpFile);
            
Solution2 solution = dte.Solution as Solution2;
            
string templatePath = solution.GetProjectTemplate("WindowsApplication.zip", "CSharp");
            
Project proj = solution.AddFromTemplate(templatePath, tmpDir, "dummyproj", false);
            
// add the control to the toolbox.

            EnvDTE.Window window = dte.Windows.Item(EnvDTE.Constants.vsWindowKindToolbox);
            EnvDTE.
ToolBox toolbox = (EnvDTE.ToolBox)window.Object;
            EnvDTE.
ToolBoxTab myTab = toolbox.ToolBoxTabs.Add(<Toolbox TabName>);
            myTab.Activate();
            myTab.ToolBoxItems.Add(

"MyUserControl", ctrlPath, vsToolBoxItemFormat.vsToolBoxItemFormatDotNETComponent);
            dte.Solution.Close(
false);
            
Marshal.ReleaseComObject(dte);
            
Console.WriteLine("Control Installed!!!");
        }


        void UninstallControl()
        {
            

Type type = System.Type.GetTypeFromProgID("VisualStudio.DTE.8.0");
            
DTE dte = (DTE)System.Activator.CreateInstance(type, true);
 
            EnvDTE.

Window window = dte.Windows.Item(EnvDTE.Constants.vsWindowKindToolbox);
            EnvDTE.
ToolBox toolbox = (EnvDTE.ToolBox)window.Object;
            EnvDTE.
ToolBoxTab myTab = toolbox.ToolBoxTabs.Item(<Toolbox Tabname>);
            myTab.Activate();
            myTab.Delete();
            


Marshal.ReleaseComObject(dte);
            
Console.WriteLine("Control Uninstalled!!!");
        }
       

void Register()
        {
           

IOleMessageFilter oldFilter;
            CoRegisterMessageFilter(
this, out oldFilter);
        }
       

void Revoke()
        {
            

IOleMessageFilter oldFilter;
            CoRegisterMessageFilter(
null, out oldFilter);
        }


        #region IOleMessageFilter Members
        
public int HandleInComingCall(int dwCallType, IntPtr hTaskCaller, int dwTickCount, IntPtr lpInterfaceInfo)
        {
            

return 0; //SERVERCALL_ISHANDLED

        }
        
public int RetryRejectedCall(IntPtr hTaskCallee, int dwTickCount, int dwRejectType)
        {
            

if (dwRejectType == 2) // SERVERCALL_RETRYLATER

            return 200; // wait 2 seconds and try again

            return -1; // cancel call

        }

        public int MessagePending(IntPtr hTaskCallee, int dwTickCount, int dwPendingType)
        {
            

return 2; //PENDINGMSG_WAITDEFPROCESS

        }

        #endregion

    }
}