Download the folder using the icon of iTunes 9: http://dl.maclife.com/olditunesicon.zip.
1) First you should backup the iTunes 10 icon in case you may need it later. Open the application folder and select the iTunes application. Next open the information window of the selected application (press command-I or go to File->Get Info in the menu bar). The info window will pop up with the iTunes 10 icon at the top. Select the icon and just copy it (e.g. by pressing command-C). Create a new folder somewhere in the Finder and open the info window for it. Paste iTunes 10 icon over the default folder icon (e.g. by pressing command-p).
2) Now copy the iTunes 9 icon of the attached folder and paste it over the icon of the iTunes 10 application as done previously. If you're not fully authorized to change application folders you may need to change the access privileges at the bottom of the info window. Unlock lock and change privilege to Read & Write. You will be asked for your password. Remember to undo this changes after pasting the iTunes 9 icon.
3) The iTunes icon will not automatically change in the dock. You need to remove the icon from the Dock, start iTunes and tick the "Keep in Dock" again (right click on the icon, select options).
If you're not fully satisfied with the icon only, there is a possibility to change the whole appearance of iTunes 10. More info here: http://www.macstories.net/mac/want-itunes-9-look-back-theres-a-mod-for-t...
Moreover, like explained above it works for every icon. Here are some links for downloading other icons:
- http://iconfactory.com/home
- http://interfacelift.com/icons/downloads/date/any/
- http://weloveicons.com/
- http://www.mac-icons.com/