NBA 2K6

the easiest way to do this is to go into the options menu and go to game slider and crank all of your stats up and lower the stats for the AI. then start a game as one of the 100% teams and play against the worst team. set the time to a 12min YOU WILL GET THE ACHIEVEMENT THIS WAY

Here's what worked for me, hope it helps...

As stated in the solutions above above; drop the opposition sliders, max your own, then pick a strong team to play as like West All Stars & choose a rubbish team for the CPU (Raptors for example).

Make sure the time is set to 12 mins before you start. I completed this achievement last & needed nearly all of the remaining time.

During the match, launch a long shot from just inside the opposition's half. Most of the time it will miss, then bounce back into play. Simply collect the rebound, shoot & score. You shouldn't miss, especially with your sliders all maxed.

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** EDIT 05/01/2011 **
I've found out from a mate (Dutty UK - not a member here but credit where it's due) that rebounds off your own net count as well. Now I didn't notice this myself but he said it worked for him.

He described that any shot which rebounds off your own net (which is pretty much any shot the opposition take if you have dropped their sliders) simply collect to earn a rebound. You can check the stats at any point during the game.

I haven't been able to test this myself as I already have the achievement but I'm assured it works.

Good luck.

This is by far the easiest and sure fire way to get rebounds, though i did use 2 controllers but you can do this against AI.

Firstly as you will have already done you want the user sliders set to max (Bar injuries) and the CPU sliders to minimum.
At the same time go into the NBA Rules menu and turn the following OFF:
Shot Clock
Out Of Bounds
Backcourt
8sec Half Court
3 In The Key
5sec Back To Basket

Now with these rules off pick the player you want to get your 20 rebounds with and get possession of the ball (Getting your steals here would be a good idea so that you can achievement the Get A Triple-Double in NBA 2K6 achievement).

With possession of the ball run () into you half of the court and behind your net making sure to stand in front of the pole for your basket, press the button to shoot which 99% of the time will hit the back of the basket and land near you, this counts as a rebound even though it is off your own net. Now run to the opponents net stand in the 3 point zone (Outside the red line) and hold to shoot (With the sliders all the way up you will always score)

Repeat this 20 times with the same player and you will have you 20 rebounds.
(And 60 points with one player, 20 steals with one player, 20 3-pointers scored with one player, all of which will all but complete the game for you, all that will be left is to score 140 points in the game to complete it)

You can check the stats by pausing, going into Game Stats - Home Team.

Here's a video showing the method.

As other have said put all your sliders up except both Injury slider and all the opposition down and put the game time to at least 10 minutes per quater.

The one thing I would add is if you are having problems with the rebounds then I would put 3pt Sucess right down at around a third, then every time you get the ball try a 3pt shot, it will almost always fail and around 3/4 of the time one of your own players will pick up the ball and score, I got it after around 25 minutes and after the end of the 40 minute match 3 players had got it....

(oh and you don't get the Accy until the end of the match but you will know that you have it because a VIP crib card will flash up on the screen)

I haven't won this cheevie yet but what i have worked out is that :-
* you have to turn down 3pt success but turn up 3pt tendencies.

* have the rest of the sliders turned up except injurys

* throw a 3pter make sure you have a player in the area to catch the rebound get the same person to catch the ball 20 times the cheevie will pop at the end of the match.

* its better to make a longer match 10-12 mins per quarter turn auto subs off if possible

I know it's an old game, but hey it's a quick 1k for an hour's play, as all the solutions above mention, spot on, only one tiny detail which was left out for the "20 rebounds achievement" and that is that you have to set the sub's to manual otherwise you will find your star man who's on 12 rebound's will all of a sudden be subbed due to fatigue, runny nose, parking ticket-whatever, at which time the clock's ticking. Once set to manual your then ok with your ideal line up, (same player's throughout all 4 quarters) i know it sounds obvious, but it took me all of 2 quarters to realise the player turn around time, then it becomes frantic to get said amount of rebound's, but that's just me, you may enjoy the pressure, either way, just a little tip.

I did the out of bounds off, shoot off your own back board trick for 23 rebounds, then quit the game from menu (I had a second controller plugged in thinking u have to get stats against cpu) and this cheevo popped with the rest except triple double. That was weird. I didnt even meet the requirements for scoring 140 points with a team or 50 with a player, or make 15 three pointers. I only shot 3 or 4 three pointers. It kind of reminded me of the Fifa 2006 glitch to get all the cheevos in one pop. Hope this helps any one digging through the "crates" for achievements. This took me like 7 mins total for all 1000 pts.