Try disconnecting the Yaw sensor instead... I'm guessing it will COMPLETELY disable the ESP as Woody across the pond has shown he can do donuts in the dirt with that one sensor disconnected.

It's not super easy to get to, but not really hard either. Two screws in the center console storage area and a few screws under the shifter trim. Lift the center console up a bit and it's located just behind the shifter (toward the rear of the car from the shifter). You may want someone else to hold the console up while you disconnect it. I'm going to be playing with wiring in a switch or relay on the Yaw sensor to disable it easily.

Good luck!