libusb installation failure (& workaround) while downgrading to iPhone OS 3.1.3

I was following Cory Bohon's instructions at Mac|Life for downgrading your iPhone to OS 3.1.3 when I ran into a little snag while trying to install libusb in the first step: the installer would hang on the "Preparing to install…" message.

Since libusb is a simple library, installing it manually isn't difficult and the files you need are already in the libusb.pkg file. To install them:

  1. Control-click the libusb.pkg file and select Show Package Contents.
  2. In the Contents folder, select the Archive.pax.gz file and copy it to your ~/Desktop.
  3. Double-click it to unarchive the archive.
  4. Copy the contents of the resulting usr folder to the actual /usr folder. You can do this using Terminal with the commands below. That's it, libusb is now installed and you can continue with the rest of the instructions on Mac|Life.

sudo cp ~/Desktop/usr/local/bin/* /usr/local/bin/
sudo cp ~/Desktop/usr/local/include/* /usr/local/include/
sudo cp ~/Desktop/usr/local/lib/* /usr/local/lib/
sudo cp ~/Desktop/usr/local/lib/pkgconfig/* /usr/local/lib/pkgconfig/

After installing libusb and following the other instructions on Mac|Life, I was able to successfully downgrade to OS 3.1.3.

One warning: I wasn't able to restore my latest restore – I got an error telling me that my OS version was too low. (I had to install my last 3.1.3 backup instead.) Caveat emptor.

Hope this helps if you run into the same issue.