Early Macbook Air buyers were the first to receive a read-only USB restore drive, rather than a traditional DVD. With the release of Lion, those USB drives have now become somewhat obsolete (especially if you've already upgraded to Lion). While Apple does have a Lion USB disk for sale, it costs a whopping $69. We'll show you how to unlock that Snow Leopard restore drive and upgrade it to Lion, after the jump.
The app you need in order to unlock the Snow Leopard disk is a Windows application. You can use a virtual machine or Boot Camp (in my case, I used a friend's computer, as it only took 2 minutes to complete the process).
1. This first step will show you how to save the restore disk icon. Once you plug in the restore disk, you get a nice icon that you will lose once you unlock the drive. Here is one method if you want to save that image. Create a new folder on your desktop. Right click the folder you just created and select Get Info. Do the same with the Snow Leopard recovery disk. Select the icon on the top left and press (Command + C) to copy. Go over to the info for the new folder and while the icon is selected, press (Command + V) to paste. Once your Recovery disk is done, you simply repeat these steps in order to "paste" the icon back onto your Recovery disk.
2. Now to unlock. Download this SM32Xtest application on a Windows machine and insert your Snow Leopard Recovery disk into the USB. On the application, click Scan USB, then Start. Once that's done it should unlock the Snow Leopard Restore Disk.
3. Plug the newly unlocked restore disk into your Mac and fire up Disk Utility. From here you can reformat it to Mac OS Extended. You now have a full read/write 8GB USB drive. From here you can just use it as you would any other USB drive—it even has a nifty hole to hook it onto a keychain. If you want to continue on and make this into a Lion restore disk, you have a few options which you can find here in our previous post, 3 Ways to Create a Lion Recovery Disk For Your Mac.