How to install PEAR with MAMP for OS X?

I'm trying to get PEAR working with MAMP. I'm running the following Auth example from the PEAR website:

<?php
require_once "Auth.php";

// Takes three arguments: last attempted username, the authorization
// status, and the Auth object. 
// We won't use them in this simple demonstration -- but you can use them
// to do neat things.
function loginFunction($username = null, $status = null, &$auth = null)
{
    /*
     * Change t开发者_运维知识库he HTML output so that it fits to your
     * application.
     */
    echo "<form method=\"post\" action=\"test.php\">";
    echo "<input type=\"text\" name=\"username\">";
    echo "<input type=\"password\" name=\"password\">";
    echo "<input type=\"submit\">";
    echo "</form>";
}

$options = array(
  'dsn' => "mysql://user:password@localhost/database",
  );
$a = new Auth("DB", $options, "loginFunction");

$a->start();

if ($a->checkAuth()) {
    /*
     * The output of your site goes here.
     */
}
?>

And I'm getting this error:

Fatal error: require_once() [function.require]: Failed opening required 'Auth.php' (include_path='.:/Applications/MAMP/bin/php5.3/lib/php')

I have PEAR installed and can even run pear from the command line, but I am completely stuck trying to get PEAR:Auth to run in this example code. Any help would be greatly appreciated.

You have to include PEAR path in you include_path in php.ini http://www.php.net/manual/en/ini.core.php#ini.include-path

In that path should be the file Auth.php, so you can look it up and then getting its parent directory absolute path