Desktop manager does include desktop redirector when you install it...
1. Go to http://www.blackberry.com/support/index.shtml
2. Download the latest desktop manager
3. Select the option 'BlackBerry Desktop Redirector' when asked during install
4. Open desktop manager and open redirector settings
5. Go to the advanced tab and click profile settings
6. Choose the mail (MAPI) profile that is used to connect to the Exchange server
7. Make sure desktop redirector is running. (Start > Programs > BlackBerry > BlackBerry Desktop Redirector - default install path)
8. Status on the desktop redirector window should be 'Running'
Now you should be setup on redirector. You might have to generate new encryption keys if the status is not running. Let me know how it goes.