backupwordpress plugin and heart internet

I am having issues backing up wordpress sites as I have a reseller package with Heart Internet.

I have tried using backup buddy and two other plugins to backup to dropbox but to no avail. The issue is the wp-cron.php. I have come across this plugin backupwordpress which gives a solution to get round the heart internet as below. I am not sure where to put the line they suggest as I have an eXtend panel not a cPanel.

Can anyone help, thanks

How to get BackUpWordPress working in Heart Internet

The script to be entered into the Heart Internet cPanel is: /usr/bin/php5 /home/sites/yourdomain.com/public_html/wp-cron.php (note the space between php5 and the location of the file). The file wp-cron.php chmod must be set to 711.

http://ww.wp.xz.cn/extend/plugins/backupwordpress/