That's one of the biggest complaints I have with BB user customization. One should have the ability to use whatever browser. And yes, you cannot cut and paste either. Although I still have OM on my BB, I find myself using it less and less because of these restrictions. Perhaps that's the goal anyways.
This is how I copy and paste a link from the bb browser to opera mini:
Visit the site using the bb browser. Press "P" on your bb keypad, or Menu Key>Page Address
When the pop-up window appears, scroll through your choices and choose Copy. Press the trackball to confirm your choice.
Open the opera mini browser.
Highlight and select the www. text box field with your trackball.
Without typing, scroll up or down. You will see a history of sites you've visited. Choose "Insert Symbol". It's located at the bottom of the list. The fatest way is to scroll up, as this will bypass the history links. You are now able to enter an address. Delete the "www."
Menu Key>Paste
Menu Key>OK
Press track ball or Enter to visit site.
Posted from my CrackBerry at wapforums.crackberry.com