This may be no help but, the following activates / deactivates screen saver. Can't take credit for this as it's not my code, I just know that it works !!!!
I know it's not exactly what you asked for but may point you in the right direction.
'To switch the screen saver on and off use the following code:
Private Const SC_SCREENSAVE = &HF140&
Private Const WM_SYSCOMMAND = &H112
Private Declare Function FindWindowA Lib "user32" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
'Purpose : Changes the state of the screen saver
'Inputs : bScreenSaver If True, starts the Screen Saver
' else turns the Screen Saver off
' [lHwnd] VB: The form handle OR
' [sFormCaption] VBA: The caption of the form calling the
' routine, can be Me.Caption or Application.Caption
Sub ScreenSaver(bScreenSaver As Boolean, Optional lHwnd As Long, Optional sFormCaption As String)
Dim lState As Long
If lHwnd = 0 Then
lHwnd = FindWindowA(vbNullString, sFormCaption)
End If
If bScreenSaver Then
lState = 1
Else
lState = -1
End If
Call SendMessage(lHwnd, WM_SYSCOMMAND, SC_SCREENSAVE, lState)
End Sub