to swap icons from another file/app
-Click "get info" on the folder or app you want to steal the icon from
-click the top left corner of the "get info" window, to highlight the icon
-select Edit>>copy
-now select "get info" from the file/folder you wish to change the icon for
-select the icon in the top left corner
-select edit>>paste.
The icon should copy.
To take any picture, or custom icon not already in use, it's a little more complicated.
-Install Apple Developer Tools from the OS X install disc
-Install "icns2rsrc"
From here
-It is a .SIT file, if you cannot open it, Install stuffit expander
here
Now to Begin.
-look for Icon Composer App in /developer/applications/utilities/
-Open icon composer, and drag your image into all the blank fields
-Select "use scaled version" and "Extract Mask" each time it tells you
-once all filed out, select file>save as
-put it someplace such as home/documents (create a folder for all your custom icons)
-now you have a good .icns file ! however, it's not useable yet.
-Open "Icns2Rsrc" and load the .icns file you created.
-save it in the same location.
-Now you're ready
-Use the copy/paste method I mentioned at the beginning of my post
-Done.
It is a tested method, and works fine. I did it for a folder in the finder side bar I call "applications". It now stands out really well. All it is, is a folder full of aliases pointing to the programs I use the most (including system profiler, disk utility, icon composer, etc..)
I like it that way, rather than looking through the real app folder trying to find poop.