If the above method doesn’t work for you, the free app for PPC and Intel Macs, IconDroplet, will let you switch icons on your Mac with the minimum of fuss. Visit www.macupdate.com/icondroplet to download your copy of this very useful app.

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Once downloaded, unzip the IconDroplet program so it is added to the Dock, and then find the icons you have downloaded and drag them to IconDroplet. This will create a new image file on your desktop that you will come back to in a moment.
Next, find the MacBook Pro icon you want to change in Finder, right-click and choose Get Info. Copy the file that was saved to your desktop and go back to the Info screen for the icon you wish to replace. Finish the process by selecting the icon at the top with a single mouse click and paste your replacement icon into its place!
You don’t even have to do all this though, to be honest – with the latest version of IconDroplet, you can drag new icons onto your applications as they’re running, saving a lot of messing about with cut and paste!
(Image via author)