Open your Terminal (you can find it in Applications/Utilities/) and type: cp /System/Library/CoreServices/SystemStarter/QuartzDisplay.bundle/Resources/BootPanel.pdf /
and press Return. Switch to your Finder and open your Harddrive, you will find a file called "BootPanel.pdf" there.
Make a folder "Backup" (or whatever you like) somewhere and place the file inside. Keep it.
As i dont know where you keep you downloads, just open the folder "BootPanel" you downloaded and move the
file "BootPanel.pdf" to your Desktop. Switch back to the Terminal and type: cd /Users/Your_Username_Here/Desktop/
(be sure to exchange "Your_Username_Here" to your Username) and press Return. Now you navigated with the
Terminal to your private Desktop. To move the new file into the System, type: sudo mv BootPanel.pdf /System/Library/CoreServices/SystemStarter/QuartzDisplay.bundle/Resources/
You will be asked for a Password; type in your Userpassword (you must be Admin to have the rights) and press Return.
Type "exit" (without quotations) and leave the Terminal
The new Bootpanel is placed now; Restart to use/see it.