You can change arguments passed to wall template using this hook. This hook is different then https://www.opensource-socialnetwork.org/documentation/view/5647/wall-template-view this is about arguments other one is about output template.

You may look following in OssnWall component

~~~

<?php
function my_component_init(){
ossn_add_hook('wall', 'templates:item', 'my_component_hook');
}
function my_component_hook($hook, $type, $return = null, $params){
//you may alter $params
error_log(print_r($params, true));
return $params;
}
ossn_register_callback('ossn', 'init', 'my_component_init');
~~~