So you want to use your own email on your Blackberry rather than using the default email setup by your mobile or cell phone provider? The solution is pretty simple, as it goes; and anyone should be able to get it up and running. Here's how:
Irrespective of whether you have a POP account for the email in question or not, the best way to setup the address in CPanel is to setup an email forwarder. Login to CPanel and go to "Mail" > "Email Forwarders". Then create the forwarder, providing your email name with your own domain and then int he second box, enter the email address allotted by your service provider.
Under the email settings on the Blackberry setup the "Reply-To" address as the same as the forwarding address you just created in CPanel. This way you can reply to emails with you chosen address, but will be sending them using your provider's login details, and for all intent and purpose to the recipient it will look as if it came from your forwarding address.
This is an easy fix to using your own domain and email with your blackberry and one which can be used similarly when you are having problems with SMTP relay because your ISP is blocking relay via port 25 to external mail servers to reduce SPAM traffic on thei network.