Как работать с потоками IStream в Visual Basic 6

Private Declare Function DispCallFunc Lib "oleaut32" (ByVal pvInstance As Long, ByVal oVft As Long, ByVal lCc As Long, ByVal vtReturn As VbVarType, ByVal cActuals As Long, prgVt As Any, prgpVarg As Any, pvargResult As Variant) As Long
 
Private Function DispCallByVtbl(ByVal pUnk As Long, ByVal lIndex As Long, ParamArray A() As Variant) As Variant
    Const CC_STDCALL    As Long = 4
#If Win64 Then
    Const PTR_SIZE      As Long = 8
#Else
    Const PTR_SIZE      As Long = 4
#End If
    Dim lIdx            As Long
    Dim vParam()        As Variant
    Dim vType(0 To 63)  As Integer
    Dim vPtr(0 To 63)   As Long
    Dim hResult         As Long
    
    vParam = A
    For lIdx = 0 To UBound(vParam)
        vType(lIdx) = VarType(vParam(lIdx))
        vPtr(lIdx) = VarPtr(vParam(lIdx))
    Next
    hResult = DispCallFunc(pUnk, lIndex * PTR_SIZE, CC_STDCALL, vbLong, lIdx, vType(0), vPtr(0), DispCallByVtbl)
    If hResult < 0 Then
        Err.Raise hResult, "DispCallFunc"
    End If
End Function
 
Private Function IStream_Seek(ByVal ptrIStream As Long, ByVal Offset As Currency, ByVal Origin As Stream_Seek) As Long
    Dim NewPosition As Currency
    
    IStream_Seek = DispCallByVtbl(ptrIStream, 5, Offset, Origin, VarPtr(NewPosition))
    
    If NewPosition > 0 Then
        IStream_Seek = NewPosition * 10000@
    End If
End Function

Private Function DispCallByVtbl(ByVal pUnk As Long, ByVal lIndex As Long, ParamArray A() As Variant) As Variant
    Const CC_STDCALL    As Long = 4
#If Win64 Then
    Const PTR_SIZE      As Long = 8
#Else
    Const PTR_SIZE      As Long = 4
#End If
    Dim lIdx            As Long
    Dim vParam()        As Variant
    Dim vType(0 To 63)  As Integer
    Dim vPtr(0 To 63)   As Long
    Dim hResult         As Long
    
    vParam = A
    For lIdx = 0 To UBound(vParam)
        vType(lIdx) = VarType(vParam(lIdx))
        vPtr(lIdx) = VarPtr(vParam(lIdx))
    Next
    hResult = DispCallFunc(pUnk, lIndex * PTR_SIZE, CC_STDCALL, vbLong, lIdx, vType(0), vPtr(0), DispCallByVtbl)
    If hResult < 0 Then
        Err.Raise hResult, "DispCallFunc"
    End If
End Function
 
Private Function IStream_Read(ByVal ptrIStream As Long, ByVal pv As Long, ByVal BytesRead As Long) As Long
    Dim BytesReaded As Long
    
    DispCallByVtbl ptrIStream, 3, pv, BytesRead, VarPtr(BytesReaded)
    IStream_Read = BytesReaded
End Function
 
Private Function IStream_Write(ByVal ptrIStream As Long, ByVal pv As Long, ByVal BytesWrite As Long) As Long
    Dim BytesWritten As Long
    
    DispCallByVtbl ptrIStream, 4, pv, BytesWrite, VarPtr(BytesWritten)
    IStream_Write = BytesWritten
End Function
 
Private Function IStream_Seek(ByVal ptrIStream As Long, ByVal Offset As Currency, ByVal Origin As Stream_Seek) As Long
    Dim NewPosition As Currency
    
    DispCallByVtbl ptrIStream, 5, Offset, Origin, VarPtr(NewPosition)
    IStream_Seek = NewPosition * 10000@
End Function