
Thanks to BoingBoing (love you guys!) for reporting how to do a small binary patch to enable iPod download again for iTunes 4.7:
It turns out that Apple's system for disabling the plugin uses a blacklist of disallowed iTunes additions in the iTunes binary. If you open the binary in a hexadecimal editor, like HexEdit, you can find the area where Apple has inserted the string "iPod Download" in its blacklist and simply replace the text with something else (in fact, I think you could probably just change one character) and your iTunes's original functionality will be restored.
The origin of the hack appears to be
Hardmac.com.