i got it from this link:
www.gearslutz.com/boar...post4.html
"The file should saved as x.png (where x is a three digit number between 000 and 324) and put in Users/YourUserName/Library/Application Support/Logic/Images/Icons
If no folder exists by that name, make one yourself. Be aware that some numbers are available and some will replace an existing Logic Pro icon (as long as your custom icon is in the folder)."