This is how you would install the Symantec drivers:
1. Tools --> Wizards --> Device COnfiguration Wizard
2. Next (shows you a summary of your devices, be it B2D, autoloaders, libraries etc). Click Next Again.
3. Choose the option to "Install tape device drivers", and click Next. This brings up another wizard, and you can click Next.
4. Click Next at the USB device drivers warning...
5. Make sure the first option (Use Symantec drivers for all supported tape devices" is selected, and that the Additional options has "Use Plug and Play drivers for Windows 2000 or later" selected (might not need it, but I keep it on).
6. Click Next, and let your installation run. When it detects your tape drive and asks to install the drivers, choose the option to allow. You MIGHT need to reboot your server, so be aware of that.
If you want the latest device drivers, which isn't a bad thing, use the links above to get them. Load them like a normal installation, which installs them into BE, and then do the above.