Вот все апи что для этого надо:
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hwnd As Long, lpdwProcessId As Long) As Long
Private Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAcess As Long, ByVal bInheritHandle As Long, ByVal dwProcessId As Long) As Long
Private Declare Function WriteProcessMemory Lib "kernel32" (ByVal hProcess As Long, ByVal lpBaseAdress As Any, ByVal lpBuffer As Any, ByVal nSize As Long, lpNumberOfBytesWritten As Long) As Long
Private Declare Function ReadProcessMemory Lib "kernel32" (ByVal hProcess As Long, ByVal lpBaseAddess As Any, ByVal lpBuffer As Any, ByVal nSize As Long, lpNumberOfBytesWriten As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function WriteValue Lib "kernel32" Alias "WriteProcessMemory" (ByVal hProcess As Long, ByVal lpBaseAddress As Any, lpBuffer As Any, ByVal nSize As Long, ByVal lpNumberOfBytesWritten As Long) As Long
Может даже больше