see http://answers.microsoft.com/en-us/windows/forum/windows_7-hardware/windows-7-how-to-turn-off-numlock-at-the-logon/0feb11e6-bd9e-48fa-bbb3-84ff28d9c6fd
other option would be to create a new numlock alternative combination with custom firmware
other option would be to create a new numlock alternative combination with custom firmware