PEAR on Windows: How to change pear.ini location

Question

I am trying to install a PEAR package into my recent XAMPP PHP installation (PHP 5.3.1) on Windows 7 64-bit.

Installing new packages fails because PEAR tries to access <

Answer 1

Not entirely sure but PEAR registered the following keys in the registry of my machine

REGEDIT4
[HKEY_CURRENT_USER\Environment]
"PHP_PEAR_SYSCONF_DIR"="D:\\webserver\\xampp\\php"
....

And PEAR/Config.php contains the following code snippet:

if (getenv('PHP_PEAR_SYSCONF_DIR')) {
    define('PEAR_CONFIG_SYSCONFDIR', getenv('PHP_PEAR_SYSCONF_DIR'));

and the constructor for the Config class

function PEAR_Config($user_file = '', $system_file = '', $ftp_file = false,
                         $strict = true)
    {
        $this->PEAR();
        PEAR_Installer_Role::initializeConfig($this);
        $sl = DIRECTORY_SEPARATOR;
        if (empty($user_file)) {
            if (OS_WINDOWS) {
                $user_file = PEAR_CONFIG_SYSCONFDIR . $sl . 'pear.ini';
            } else {
                $user_file = getenv('HOME') . $sl . '.pearrc';
            }
        }

$user_file = PEAR_CONFIG_SYSCONFDIR . $sl . 'pear.ini'; seems to be the line that makes "my" PEAR installation use the file D:\webserver\xampp\php\pear.ini.
If that's correct all you have to do is to somehow set the environment variable PEAR_CONFIG_SYSCONFDIR