Once again, if it's a company device, they own it and they can make the rules. If it's your device, keep it off the corporate BES or you lose control of it... not to mention the BES admin's ability/right to view and monitor anything you do on the device.
You may be able to find ways around the company policies, including the BlackBerry IT policy, but that "freedom" will be short lived, and possible at the expense of your employment - or vice versa. People have been terminated for less that what you are trying to do.
You have been warned by several members here, so you can't say that you didn't know if/when it happens. Good luck to you.