Here is a screenshot from the guy who did it, ronaldmonster, from the ZuneRama forums:
(click the image for big version)

The way to do this is the following according to the creator:

Make sure your HDD hack is installed before you do anything.

Set EnableLegacySupport in the registry to 2 before anything.

Right click my computer and click Manage.

Click Device Manager and on that screen click Portable Devices and right click Zune and Update Driver & click Advanced.

Then click the bubble saying "I will choose what Driver To Install".

Un-check show compatible hardware.

At the very top of manufacturers on the left choose the Standard MTP-Compliant.

Finish the install, some windows will pop-up pretty obvious as to what there meant to do. But the problem from I've messed around with is this, it is that stupid locked state. When you try to sync content it gives you an error message. 

The sync fails because Zune checks for a 16 bytes authentication code that the Zune Software sends to it. Without this the user can only view the contents of Zune or delete them but not to read/write them. This is a major barrier stopping Zune from working with alternative Sync Software on Windows, but also on Mac & Linux.

Read more on this relevant thread on our forums, talking about the using Zune with Amarok and libmtp on Linux .

An ongoing project you hackers can check is gZune, which tries to replicate tha sync process between Zune Software and Zune. Talking some weeks ago with his author, Albinotux, he told me this 16 bytes code is where he has stopped.

You can download the full source code of gZune and try to bypass it. It is written on C-Sharp (C#) and you can download a free compiler from Microsoft. Any volunteers ?

[via Crunchgear & ZuneRama ]

Related articles:
Zune Hacks & Tricks