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');