I did get this to work. The .Net user control can be hosted in VB6,VBA web forms,but not,I found,all ActiveX containers. Here are the details for those interested in what I did.

1. Create a VB.NEt user control (VB 2005)
2. Put a button on the control
3. Set project property "Register for COM interop"
4. Modify the usercontrol1.vb as show below
BUILD VB.Net user control which will register the ActiveX control
5. In VB6,add control (assembly namespace.MyControl")
Code:
Imports System.Runtime.InteropServices
Imports System.Text
Imports System.IO
Imports System.Reflection
Imports Microsoft.Win32
Imports System
Imports System.Threading
Imports System.Math

<ComClass(MyControl.ClassId,_
MyControl.InterfaceId,_
MyControl.EventsId)> _
Public Class MyControl
' MAKE SURE WE HAVE 1 PUBLIC SUB in this class

#Region "COM GUIDs"
' These GUIDs provide the COM identity for this class
' and its COM interfaces. If you change them,existing
' clients will no longer be able to access the class.
'You should create your own 3 GUIDS using GuidGen
Public Const ClassId As String = "8D6CC4E9-1AE1-4909-94AF-8A4CDC10C466"
Public Const InterfaceId As String = "D901FC53-EEC2-4634-A1B5-BB4E41B24521"
Public Const EventsId As String = "7458968F-F760-4f53-A2E4-30C1D8CD691B"
#End Region

#Region "required FOR ACTIVEX"
' This function is called when registered (no need to change it)
<ComRegisterFunction()> _
Private Shared Sub ComRegister(ByVal t As Type)
Dim keyName As String = "CLSID\\" & t.GUID.ToString("B")
Dim key As RegistryKey = Registry.ClassesRoot.OpenSubKey(keyName,True)

key.CreateSubKey("Control").Close()
Dim subkey As RegistryKey = key.CreateSubKey("MiscStatus")
subkey.SetValue("","131201")
subkey = key.CreateSubKey("TypeLib")
Dim libid As Guid = Marshal.GetTypeLibGuidForAssembly(t.Assembly)
subkey.SetValue("",libid.ToString("B"))
subkey = key.CreateSubKey("Version")
Dim ver As Version = t.Assembly.GetName().Version
Dim version As String = String.Format("{0}.{1}",ver.Major,ver.Minor)
If version = "0.0" Then version = "1.0"
subkey.SetValue("",version)

End Sub

' This is called when unregistering (no need to change it)
<ComUnregisterFunction()> _
Private Shared Sub ComUnregister(ByVal t As Type)
' Delete entire CLSID¥{clsid} subtree
Dim keyName As String = "CLSID\\" & _
t.GUID.ToString("B")
Registry.ClassesRoot.DeleteSubKeyTree(keyName)
End Sub

#End Region
Private Sub UserControl1_Load(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles MyBase.Load

End Sub

Public Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click MessageBox.Show("OK") End Sub End Class