Como actualizar la arquitectura de 32 bits de un archivo a 64 bits para excel

Tengo el siguiente código:

Public Declare Function FindWindowA Lib "user32" _
(ByVal lpClassName As String, ByVal lpWindowName As String) As Long

Public Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" _
(ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long

Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _
(ByVal hWnd As Long, ByVal nIndex As Long) As Long

Mi sistema operativo es de 64 bits, como lo puedo actualizar.