The following wrapper function can communicate with the Phish.net API using cURL. Include this function in any page to establish a connection with phish.net.
<?php
$myapikey ='XXXXX';
function pnet_api_req($data) {
    $ch = curl_init('https://api.phish.net/api.js');
    curl_setopt($ch, CURLOPT_POST,true);
    if(is_array($data)) { $data = http_build_query($data); }
    curl_setopt($ch, CURLOPT_POSTFIELDS,$data);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION,1);
    curl_setopt($ch, CURLOPT_HEADER,0);  // DO NOT RETURN HTTP HEADERS
    curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);  // RETURN THE CONTENTS OF THE CALL
    return curl_exec($ch);
}

The next step is to send data to the function. Here is an example method call:
<?php
$data = [
    'method'=>'pnet.forum.thread.get',
    'apikey'=>$myapikey,
    'format'=>'json',
    'api'=>'2.0'
];
$arr = @json_decode(pnet_api_req($data),true); //set to true for an array or false for an object
if(is_array($arr)) { print_r($arr); } else { echo '<p>Unable to fetch phish.net API</p>'; }

This should provide you the infrastructure to communicate with the phish.net API using any method, including the writeable methods.