cPanel offers two options for installing PDO – using EasyApache which can enable PDO and MySQL’s PDO driver or installing everything via PECL. Unfortunately, under PHP 5.3, the PECL installers don’t work, so if you need any other PDO drivers, you’re in a hole.
Luckily, you can install it manually.
Download the PDO driver from the PECL website. Extract the archive and CD into the directory.
wget http://pecl.php.net/get/PDO_PGSQL tar -xzf PDO-PGSQL-1.0.2.tgz cd PDO-PSQL-1.0.2/
Once this is done, run the standard commands for building a PHP extension.
phpize ./configure make make install
Once this is done, you can add the extension to php.ini.
cd /usr/local/lib/ vim php.ini extension=pdo_pgsql.so
Finally, restart Apache and the Postgres driver should show up in your phpinfo() output.