[Dead Eddie]

Here's basically the same thing being called from an internal script.

PHP Code:

<?php

//stolen from index.php
define('VB_ENTRY', 1);
require_once('includes/vb5/autoloader.php');
vB5_Autoloader::register(dirname(__FILE__));

$app = vB5_Frontend_Application::init('config.php');

error_reporting(E_ALL | E_STRICT);

$config = vB5_Config::instance();
if (!$config->report_all_php_errors) {
    error_reporting(E_ALL & ~(E_NOTICE | E_STRICT));
}

$api = Api_InterfaceAbstract::instance();

$input = [
    'title'        =>    'Posting through the API',
    'rawtext'    =>    'My really cool API Post',
    'nodeid'    =>    0,
    'parentid'    =>    3,
    'channelid'    =>    3,
    'ret'        =>    '',
    'tags'        =>    '',
    'reason'    =>    '',
    'iconid'    =>    '',
    'prefixid'    =>    '',
    'hvinput'    =>    '',
    'subtype'    =>    '',
    'userid'    =>    '1',
    'username'    =>    'User',
];

$options = [];

$nodeId = $api->callApi('content_text', 'add', [$input, $options]);


if(!is_int($nodeId))
{
    print_r($nodeId);
    exit;
}
print 'Node '. $nodeId . ' created successfully';

This is still just an example of the frontend calling the API. Is this what you're looking for? Or are you trying to call it externally?