Using flickr.photos.search method of the API with your user_id does not work ?
For PHP, you have a PEAR-based package here and another library at http://phpflickr.com/. Should be enough to get through it.
EDIT :
For minimal implementation you should use stream_context_create() with HTTP headers, use fopen()
with this context and build a XMLRPC request by hand as a text variable that you will send. Answer from the socket will be your data
For the API, use flickr.photosets.getList
CODE EXAMPLE (you need a valid api key for flickr)
<?php
$apiKey = '';
$userID = '';
$url = 'http://api.flickr.com/services/rest/?method=flickr.photosets.getList&api_key='
.$apiKey.'&user_id='.$userID.'&format=json';
$options = Array('http' => Array('method' => 'GET'));
$context = stream_context_create($options);
$response = file_get_contents($url, false, $context);
$object = json_decode($response);