This info comes from my '98 FSM, so it may be wrong for your year, but you should be able to tap into the dark blue wire with a white stripe anywhere between the TCU and the transmission and feed the transmission 12 volts on this wire. This *should* lock the TC, if it does not, you have a bad solenoid (again!?) bad wiring anywhere between where you tap into the wire, or a problem in the valve body / transmission hydraulics.