Code:
Private Declare Function GetSystemDirectory Lib "Kernel32" Alias "GetSystemDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long) As Long
Private Property Get systemdir$()
    Dim str As String * 256, length&
    length = GetSystemDirectory(str, 256&)
    systemdir = Left(str, length)
End Property


'You shell RegSrv32.exe in system directory:
Shell systemdir & "\Regsvr32.exe /s " & YouOCXpath