@sabrahamse The command looks correct but you should change the command to capture the output, otherwise you have no way of knowing what is failing
php /home/sachm/public_html/phplist/admin/index.php -pprocessqueue
-c/home/sachm/public_html/phplist/config/config.php >~/processqueue.log 2>&1
This will create a file in your cpanel home directory named processqueue.log.
But possibly php might be the wrong command to run php, I often use php-cli for cpanel