Import a certificate from your computer using a USB connection

If USB file sharing is not turned on, on your BlackBerry PlayBook tablet, tap > Storage and Sharing. Set the USB Sharing switch to On. To set a password to help protect your data, tap Password.
Connect your tablet to your computer using a USB cable.
On your tablet, tap > About.
In the drop-down list, tap Network and make note of the USB IPv4 address for your tablet.
On your computer, navigate to your tablet IPv4 address.
In a separate file browser window, navigate to and copy the certificate.
On the tablet drive on your computer, navigate to the Certs folder and paste the certificate.
Tap Next.
On your tablet, swipe down from the top frame.
Tap Security > Certificates > Import.