Ok i found the icons in /Applications/iTunes.app/Contents/Resources/iTunes.rsrc file, but I don't know how to pull them out. Most of applications that read .rsrc files are outdated and don't work on intel Mac. The only working one I found (ResFork) seems to be read-only.
Any idea how to pull a .png from .rsrc file on Intel-based Mac? Or is there someone with older Mac who could do this?