There is a very neat way of doing it, and it's quite simple. Just follow the below steps and you will be all set within a few moments.

1. Login to your /WHM
2. Go to: cPanel >> Install cPAddons
3. Vendor's information URL: http://www.boonex.com/cpaddons/sync/
4. Then go ahead and set it to "Update Vendors"
5. The BoonEx "DolphinFree and DolphinAdFree" will be automatically in available in the list. Tick the checkbox near each item (mentioned above) and press "Update Addon Config" button.
6. Once all the above operations are completed, Dolphin will be available to install from the users cPanel.