Just tried the following and seems to work.
Navigate yourself to wp-favorite-posts.php of the plugin.
Make a copy of wpfp_link function below and add the post_id as an argument.
e.g From
function wpfp_link( $return = 0, $action = "", $show_span = 1, $args = array() )
To : function wpfp_link_by_id( $post_id , $return = 0, $action = "", $show_span = 1, $args = array())
Comment the $post_id = &$post->ID; in line 3 of the function.
Then simple call it like this wpfp_link_by_id($post_id)
Please note that any future update will erase your changes.
I hope it helps if there are any problems with the above solution let me know.
