NOTE #1: This procedure WILL trip the Knox flag.
NOTE #2: It is advisable that you do not connect your Tab Pro 8.4 to your computer until reaching Step 7.
Download Samsung USB Driver for Mobile Phones (Windows Only):
Samsung's Website (you'll have to search a generic device, like Galaxy S4, in order to find the driver)
Tab 8.4 Download CF Auto-Root (8.4)
Tab 10.1 Download CF Auto-Root (10.1)
Extract files to a folder on your desktop, open newly created folder, run Odin.
In Odin, for the Tab 8.4, choose "PDA" and select the file "CF-Auto-Root-mondrianwifi-mondrianwifixx-smt320.tar.md5" (included in the CF Auto-Root zip)
For the Tab 10.1, choose "PDA" and select the file "CF-Auto-Root-picassowifi-picassowifixx-smt520.tar.md5" (included in the CF Auto-Root zip)
Power off your Tab.
On your Tab, hold the Power and Volume Down buttons until you see a "Warning!!" screen with a large yellow triangle at the bottom. Press Volume Up to continue.
Connect your Tab to your computer using the supplied USB cable.
Your computer should now automatically install the appropriate drivers for use in the Tab's "Download Mode".
In Odin, verify that your Tab is connected to a COM port (yellow box with text "COM x" where "x" is a number)
In Odin, press "Start"
Upon a successful flash, Odin will display "PASS" and your Tab will reboot.
You can expect to have to disable Knox, and SuperUser should prompt you to do this.
Be sure to thank @Chainfire; he's an amazing contributor to all that is Android.