Code:
lynx --dump [url]http://yoursite.com/cronjob.php[/url] >/dev/null
lynx is a text based web browser that is on pretty much every linux system. This will visit the url as needed

And execute the script, and in cpanel just select the times you need and your done
If you need any further help, let me know.
BTW, i would put like
http://yoursite.com/cronjob.php?password=thepassword
for the url, this way you dont get unwanted users execting your script.
And if you want to get fancy, get your servers ip address and write a php script to only allow it to execute it if the ip address matches the server ip address.
Just private message me, or contact me via messager from my profile if you need anything.
Rep please

Cody