You can override the entire profile page content with custom content. (You may also use page override hook but that doesn't contain user instance).

~~~
<?php
function my_component_init(){
ossn_add_hook('profile', 'load:content', 'my_component_hook');
}
function my_component_hook($hook, $type, $oldcontents, $vars){
//$vars['user'] contains user instance (OssnUser)
return 'your new contents';
}
ossn_register_callback('ossn', 'init', 'my_component_init');
~~~