The easiest way would be to use a rule in you mail file. As an explanation, the mail must arrive in your inbox for it to go to your work blackberry, rules only happen after they arrive there. Have you Notes mail client, using a rule, send the mail you want on your personal blackberry by using a forwarding rule.
Notes help is capable of showing you how to setup the necessary rule, but feel free to ask questions if you need further assistance.
In many ways, even better than a rule is to create a agent on the server copy of your mail file. This way you don’t even need your client/computer even turned on. Also some organizations block you from forwarding to outside addresses and your rule will not work. Agents are more powerful and you can apply more logical conditions.