Use API functions to register the program as a server process. This does not seem to work in Windows NT.

Private Declare Function GetCurrentProcessId Lib "kernel32" _
    () As Long
Private Declare Function GetCurrentProcess Lib "kernel32" _
    () As Long
Private Declare Function RegisterServiceProcess Lib _
    "kernel32" (ByVal dwProcessID As Long, ByVal dwType As _
    Long) As Long

Private Sub chkVisible_Click()
    taskVisible chkVisible.Value = 1
    If chkVisible.Value = 1 Then
        Caption = "Visible To Ctrl+Alt+Del"
    Else
        Caption = "Invisible To Ctrl+Alt+Del"
    End If
End Sub

Private Sub Form_Load()
    taskVisible False
End Sub

Public Sub taskVisible(visible As Boolean)
Dim lI As Long
Dim lJ As Long

    lI = GetCurrentProcessId()
    If Not visible Then
        lJ = RegisterServiceProcess(lI, 1)
    Else
        lJ = RegisterServiceProcess(lI, 0)
    End If
End Sub