I came across this on the internet a few days ago. I had a chance to try it out on my car and I can tell you that it does work. It will be useful when taking your car to a dyno. You won't need to remove the fuse for the traction control, you can just disable it yourself.
Also, for the guys that race their TS' s....I'm sure you won't have to worry about the traction control stepping in and cutting the power when launching. I haven't tried this on my car and I wouldn't do it so I can't confirm if it will benefit you.
Below are the steps to follow in order to disable the traction control and stability control
To start off, engine must be off and handbrake must be down
1. Put the key in "contact" (press start button once-orange light will come on)
2. Clutch downwards
3. Handbrake on (up)
4. Start engine
5. Push twice on the feet brake and by the second time keep it down.
6. Handbrake off (down), handbrake on (up),handbrake off (down), handbrake on (up)
7. Again push twice on the feet brake and by the second time NOT keep it down.
TRC and VSC lights go on. Both systems now off.
To put the systems ON simple switch off the engine. When you start again the systems are working normal.
Here is a pic of my cluster aftet the above steps were followed
Current : 2007 Ford Ka 1.3
EX : 2001 Toyota Corolla 160i GLE