Download and add FirePHPCore directory in a lib directory - https://github.com/firephp/firephp-core/tree/master/lib/FirePHPCore
Install and activate FirePHP extension in Firefox or FirePHP4Chrome for Chrome.
Add lib directory to include path and include the fb.php file. In require, use the relative path to the file.
set_include_path(dirname(dirname(__FILE__)).'/lib' . PATH_SEPARATOR . get_include_path());
require 'FirePHPCore/fb.php';
Use functions to view in console:
FB::log( $variable, 'variable' );