[ComImport]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("79EAC9E5-BAF9-11CE-8C82-00AA004BA90B")]
public interface IInternetProtocolSink
{
    void Switch(ref _tagPROTOCOLDATA pProtocolData);
    void ReportProgress(uint ulStatusCode, [MarshalAs(UnmanagedType.LPWStr)] string szStatusText);
    void ReportData(BSCF grfBSCF, uint ulProgress, uint ulProgressMax);
    void ReportResult(int hrResult, uint dwError, [MarshalAs(UnmanagedType.LPWStr)] string szResult);
[Guid("79EAC9E4-BAF9-11CE-8C82-00AA004BA90B")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IInternetProtocol {
    //IInternetProtcolRoot
    void Start(
        [ MarshalAs(UnmanagedType.LPWStr) ] string szURL,
        IInternetProtocolSink Sink,
        IInternetBindInfo pOIBindInfo,
        UInt32 grfPI,
        UInt32 dwReserved);
    void Continue(ref _tagPROTOCOLDATA pProtocolData);
    void Abort(Int32 hrReason, UInt32 dwOptions);
    void Terminate(UInt32 dwOptions);
    void Suspend();
    void Resume();
    //IInternetProtocol
    [PreserveSig()] UInt32 Read(IntPtr pv, UInt32 cb, out UInt32 pcbRead);
    void Seek(_LARGE_INTEGER dlibMove, UInt32 dwOrigin, out _ULARGE_INTEGER plibNewPosition);
    void LockRequest(UInt32 dwOptions);
    void UnlockRequest();
}

VB Definition:

<ComImport(), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("79EAC9E5-BAF9-11CE-8C82-00AA004BA90B")> _

Public Interface IInternetProtocolSink

    Sub Switch(ByRef pProtocolData As _tagPROTOCOLDATA)
    Sub ReportProgress(ByVal ulStatusCode As UInt32, <MarshalAs(UnmanagedType.LPWStr)> ByVal szStatusText As String)
    Sub ReportData(ByVal grfBSCF As BSCF, ByVal ulProgress As UInt32, ByVal ulProgressMax As UInt32)
    Sub ReportResult(ByVal hrResult As Integer, ByVal dwError As UInt32, <MarshalAs(UnmanagedType.LPWStr)> ByVal szResult As String)

End Interface

<ComImport> _
<Guid("79EAC9E4-BAF9-11CE-8C82-00AA004BA90B")> _
<InterfaceType(ComInterfaceType.InterfaceIsIUnknown)>
Interface IInternetProtocol
TODO
End Interface