The Maximum height you can make in-game when you create a player is 7'6, but.....
You can make a player that stands 30-ft or much taller/smaller.
How to make it? It's very easy.
First, you need NBA LIVE 08 editor v2.3 by Ayiep, you can see it on the Downloads section.
You can also do this trick on other NBA Live Games (05,06,07,08)
1. Open your NBA LIVE 08 EDITOR v2.3
2. Create a new player and change his height to 360 inches (30 feet)
Other notable heights: 1 inch player (1 inch), 8 feet (95 inch), 9 feet (107 inch)
3. Save the roster
4. Load the roster in-game.
5. Start a new game/practice/1on1 game and Have fun!
(I prefer Yao Ming vs. your 30 foot player)
Hope i helped, you can type any other height you prefer.
Note: There is no limit, It will not crash even if you make a player 100 feet.
If you make a player an inch tall, you will not be able to see him, only his shadow, but it's ridiculous and fun as you can break their ankles fast, try simulating and experimenting, Have Fun!
PREVIEW (SORRY for low resolution)