I found this:

You use System Reflection to dynamically load a control. If the DLL is named
"SpecControls.DLL" and the class you want is "SpecControls.ColorControl",
then use this code.

[C#]

    // load the assembly
    System.Reflection.Assembly assembly =
Assembly.LoadFrom("SpecControls.DLL");

    // get the type
    Type t = assembly.GetType("MyControls.MyControl");

    // create an instance and add it.
    //
    Control c = (Control)Activator.CreateInstance(t);
    parent.Controls.Add(c);

[VB.NET]

     ' load the assembly
    Dim assembly1 As System.Reflection.Assembly =
Assembly.LoadFrom("SpecControls.DLL")

    ' get the type
    Dim t As Type = assembly1.GetType("MyControls.MyControl")

    ' create an instance and add it.
    '
    Dim c As Control = CType(Activator.CreateInstance(t), Control)
    parent.Controls.Add(c)

If you have any better ideas let me know!