Yes, it's been posted before, many, many times, so it's not like it's not there, you just have to look a little harder next time kobesteak.
The backdown button has been replaced with an analog stick direction in NBA Live 06. So if you have a controller with an analog stick, all you got to do is hold it down.
If you only have got a keyboard, you can just follow this tutorial to ad a button for it on your keyboard:
http://www.nbaliveforums.com/sutra434353.php#434353.
And if you don't want to do that, I suggest you buy a controller or play without the backdown feature. Easy enough.
Now I do believe this thread has served its purpose, so consider it locked.