Como "un frame transparente" ? No quieres decir "un formulario transparente" ?
Si es un formulario puedes usar este codigo :
Private Declare Function GetWindowLong Lib "User32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long
Private Declare Function SetWindowLong Lib "User32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function SetLayeredWindowAttributes Lib "User32" (ByVal hwnd As Long, ByVal crey As Byte, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long
Private Const GWL_EXSTYLE = (-20)
Private Const WS_EX_LAYERED = &H80000
Private Const LWA_ALPHA = &H2&
Private Sub Command1_Click()
Dim LEVEL As Byte
LEVEL = Nivel
Call SetWindowLong(Me.hwnd, GWL_EXSTYLE, GetWindowLong(Me.hwnd, GWL_EXSTYLE) Or WS_EX_LAYERED)
Call SetLayeredWindowAttributes(Me.hwnd, 0, LEVEL, LWA_ALPHA)
End Sub
El Nivel va desde 20 - 250