NBA Live (2005-07) uses a 4 letter abbreviation to deliniate which court (or jersey) is for which team. A list of the abbreviations can be found here.
For this tutorial we will convert Andreas Dahl's amazing next-gen practice court for 06 to 07.
Download Dahl's court here.
Run the installer and locate the files. It should install to C:/Program files/EA Sports/NBA Live 06/sgsm (aka the 06 sgsm folder)
According to the abbreviation list 06's practice court abbreviation is "pgym". Locate every file who's first four characters are "pgym" in the sgsm folder.
In Live 07 the practice abbreviation is "prac" so rename all of the files that begin with "pgym" to "prac" (this is where the file renaming program can come in handy. Locate the Live 06 sgsm folder then goto the Find / Replace tab. Type in pgym in the find box and prac in the replace box.)
Now select all of the newly renamed files which should now begin with "prac". Right Click or goto the edit menu and cut or copy them. Then navigate to the Live 07 sgsm folder (c:/program files/EA Sports/NBA Live 07/sgsm) and paste the files in there.
Check to make sure all 20 of the court files got copied to the 07 sgsm.
Load up the game and enjoy dahl's amazing court!

If you have any questions post here.