The lock up is a simple 'on/off' switch signalled by the
ECU. Even has its own wire to do it. All that is needed to disable it is to fit a toggle switch after the
ECU that breaks the connection. That way the auto never gets a signal to lock up.
I recommend not messing with it in normal driving as not having a lockup is a pig on fuel.
Useful for the track though if your engine has enough power to compensate... which mine doesnt.