I'm sure most people have noticed by now that using the Show Info cut & paste method of changing an app's icon doesn't work quite as well as one would like. Specifically the app will revert to showing its original icon when in the dock. Here's how to change an apps icon(s) permanently...
To do this you may need IconComposer which can be found in /Developer/Applications after installing from the Developer CD. I say "may" because you can do it without this tool if you just want to substitute one app's icons for another's.
For this explanation we will give Sherlock the icons from Chess. Hey, its just an explanation.
Read the rest of this article if you'd like a step-by-step on replacing an app's icon more permanently than copy/paste appears to...
1) In the Finder, select Sherlock (at this point I suggest you duplicate Sherlock just to be on the safe side.)
2) Either click the RIGHT mouse button if you have one or hold down the Control key and click the only mouse button you have.
3) From the menu that appears select "Show Package Contents." A new window will open with a folder called "Contents" in.
4) Navigate to the Resources folder that is in the Contents folder. You will see a file called "Sherlock.icns". (If you have IconComposer you can double-click this file to open it up and see the icons. Click "Proceed Anyway" when you get the warning).
6) Open a new Finder window, find and select Chess, bring up the context-sensitive menu and choose "Show Package Contents."
7) Locate the file named "chess.icns"
8) Back in Sherlock's Resources folder, delete or rename "Sherlock.icns"
9) Copy "chess.icns" into Sherlock's Resources folder (where "Sherlock.icns" was) and rename it "Sherlock.icns".
10) Launch Sherlock and marvel at its new, completely inappropriate icon! By the way, you won't see the icon in Finder windows until you log out and log back in again.
That's it. If you have IconsComposer you can doble-click a ".icns" file to view and change its contents. For some reason it doesn't support pasting in images, you have to double-click one of the icons in the window and import an image file containing your icon art.
Some apps have other ".icns" files for associated documents which can be changed in the same way. I grabbed Music Player off the OS X Beta CD and gave Audion 2 all its icons.
Now I have a request. Anyone worked out how to locate and change other application resources like images etc.? Some are obvious but others, like all the icons displayed in System Preferences and the Music Player interface elements have eluded me, despite opening up various resource files in Interface Builder. Anybody know better?
Mac OS X Hints
http://hints.macworld.com/article.php?story=20010507142939988