Attached is the code used here for the home button.
And the function add_home_menu should be "attached" to the integrate_menu_buttons hook.
To do that you can, use this script:
<?php
require_once('SSI.php');
add_integration_function('integrate_menu_buttons', 'add_home_menu', 'SUBSDIR/HomeBtn.subs.php');
If you have any question/doubt feel free to ask.