$ sudo pear -D auto_discover=1 install pear.amazonwebservices.com/sdk-1.6.0
Attempting to discover channel "guzzlephp.org/pear"...
downloading channel.xml ...
Starting to download channel.xml (817 bytes)
....done: 817 bytes
Auto-discovered channel "guzzlephp.org/pear", alias "guzzle", adding to registry
Attempting to discover channel "pear.symfony.com"...
downloading channel.xml ...
Starting to download channel.xml (811 bytes)
...done: 811 bytes
Auto-discovered channel "pear.symfony.com", alias "symfony2", adding to registry
downloading sdk-1.6.0.tgz ...
Starting to download sdk-1.6.0.tgz (2,109,426 bytes)
...done: 2,109,426 bytes
downloading Guzzle-3.1.2.tgz ...
Starting to download Guzzle-3.1.2.tgz (290,301 bytes)
...done: 290,301 bytes
downloading EventDispatcher-2.1.7.tgz ...
Starting to download EventDispatcher-2.1.7.tgz (11,110 bytes)
...done: 11,110 bytes
install ok: channel://pear.amazonwebservices.com/sdk-1.6.0
install ok: channel://pear.symfony.com/EventDispatcher-2.1.7
install ok: channel://guzzlephp.org/pear/Guzzle-3.1.2