Simple, first select a player with this attribute,go inside of the key, and then hold the  button and move the  in a clockwise circular motion. Your player will then dunk the ball ( and hopefully make it) and after the replay, you will receive your achievement.

IMPORTANT- Must be done with a player that can do the highflyer move.This player must also be Level 3 at this attribute ( you can check the levels in player stats at the main menu). Look at the bottom left of the screen and you should see a circle. Make sure that the selected circle is the highflyer one. You can rotate from circle to circle by pressing both the  and  button at the same time. This goes for each of the Level 3 moves/In the Zone.

Select a player that has the shooter attribute. After highlighting this attirbute in the bottom left hand corner, make sure that your player is outside of the 3 point line. Press and hold the  and tap  for a pump fake, then rotate the right stick in a circular motion. After going in and the rplay being shown, you will receive this achievement.

-Note
I also received this achievement by holding the , pump faking by tapping , and then shooting with . I believe that this is the easier way.

ALL IN THE ZONE ACHIEVEMENTS-They must all be done with a player that is "IN the Zone". To get a player in the zone you must make a lot of points with that certain player. These achievements are exactly the same as the Level 3 ones, except your player must be In the Zone.

Play a quick game and make sure that your four controllers are even distributed onto their teams, thats two controllers to a team. You must finish the game to receive this achievement. If you don't have four controllers, then you should probably invite a friend over, because there is no way around this.

It should be noted that if you don't see a player icon over each player's head before you start that player doesn't count as a user. This seems to be triggered by using non-conventional controllers like the guitar. 

To be totally honest with you, I don't believe that you will ever get this achievement. You must be online when 999 other people are and being that it now barely even reaches 200, you might never get this achievement. My suggestion is for someone to call for a rally of people to play this game on a certain day.

 For news on this achievement, please see NBALive1000.com

Some Tips-

You can create your own athlete in the main menu and max out all of his abilities. This athlete can then be placed on your team of choice in the Team management screen. Remember to save your roster so as to not lose him from your team when you turn off the console.

Press  and  at the same to to switch between certain abilities.

If you are desperate to get the 1,000 online people call for a rally on this site.. because otherwise you will never get this.

You must make the basket to receive the Level 3 and In the Zone achievements, besides the Playmaker achievements because you are only passing the ball.

When the game is paused, go to settings and you can adjust the game sliders so that you are even better and the computer worse. This will make easier your task of getting these achievements.You can also change the settings in the main menu, and also save them so that it doesn't reset after you turn of your xbox.

Some players may have the attribute of Highflyer, Shooter, etc., but that doesn't mean that they are of a level 3 skill. You can check each of the teams and their player's abilities in the main menu to see if they are level three.

Levels-
Bronze--Level 1
Silver--Level 2
Gold--Level 3

Color of Attributes-
Light Blue- Playmaker
Purple- Scorer
Red- High Flyer
Yellow- Shooter
Green-Post

You cannot get both the In the Zone and Level 3 at the same time.. so I suggest first getting the level 3 achievements.