I just tried the method shown in the first link in my previous post and was able to successfully change the icon back to the previous iTunes version icon.
Did you download the old iTunes.icns file and open your App folder and right click on iTunes and choose "Show Package Contents"?
Then you Option+Drag the new iTunes.icns file to a location other than where you have the older on stored, to copy it, then drag the older iTunes.icn file into the finder window where the iTunes.icn file is that you want to replace.
Then you should see a window asking you whether or not you want to replace the iTunes.icn file with the newer (well it's really the older version) file.
Click yes and then remove the newer iTunes icon from your dock and go to the Applications folder and click on iTunes to launch it ... you should see the newer icon has been replaced with the one you prefer.
Once iTunes has launched, Right-Click on it's Dock icon and choose "Keep In Dock" and you should be good to go ....
Let me know how you get on