[VERY MUCH UNRESOLVED, THANK YOU iPRANK] test

[bushmobile]

In module:

Option Explicit
 
Private Declare Function SetTimer Lib "user32" _
    (ByVal hwnd As Long, ByVal nIDEvent As Long, ByVal uElapse As Long, _
    ByVal lpTimerFunc As Long) As Long
 
Private Declare Function KillTimer Lib "user32" (ByVal hwnd As Long, _
    ByVal nIDEvent As Long) As Long
 
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
    (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
 
Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
    (ByVal hwndParent As Long, ByVal hwndChildAfter As Long, _
    ByVal lpszClass As String, ByVal lpszWindow As String) As Long
Declare Function SetWindowText Lib "user32" Alias "SetWindowTextA" _
    (ByVal hwnd As Long, ByVal lpString As String) As Long
 
Private Const NV_MSGBOX As Long = &H5000&
Private sBut(2) As String, sTit As String
 
Public Function CustMsgBox(ByVal F As Form, ByVal sText As String, ByVal sTitle As String, _
                           ByVal Picture As VbMsgBoxStyle, _
                           ByVal sButton1 As String, _
                           Optional ByVal sButton2 As String, _
                           Optional ByVal sButton3 As String) As Long
    Dim N As Long, lBut As Long, lRet As Long
    sTit = sTitle
    sBut(0) = sButton1: sBut(1) = sButton2: sBut(2) = sButton3
    SetTimer F.hwnd, NV_MSGBOX, 10, AddressOf ChangeButtons
    For N = 0 To 2
        If Len(sBut(N)) Then lBut = lBut + 1
    Next N
    lRet = MsgBox(sText, Picture Or (lBut - 1), sTitle)
    If lRet > 2 Then lRet = lRet - 2
    CustMsgBox = lRet
End Function
 
Private Sub ChangeButtons(ByVal plngHandle As Long, ByVal uMsg As Long, _
                          ByVal plngEventId As Long, ByVal dwTime As Long)
    Dim lhWnd As Long, lhBut As Long, lhTemp As Long, N As Long
    
    lhWnd = FindWindow("#32770", sTit)
    For N = 0 To 2
        If Len(sBut(N)) Then
            Do
                lhTemp = FindWindowEx(lhWnd, lhBut, "Button", vbNullString)
            Loop While lhTemp = lhBut
            lhBut = lhTemp
            SetWindowText lhBut, sBut(N)
        End If
    Next N
    KillTimer plngHandle, plngEventId
End Sub

You then call it like this:

Private Sub Command1_Click()
    Dim lRet As Long
    lRet = CustMsgBox(Me, "Click a button", "MsgBox Title", vbExclamation, "button1", "button2", "button3")
    ' lRet is the number of the button pressed, either button 1, 2 or 3
End Sub