[Thinkpad Tablet General] Gramdalf:
I did this same thing, but replaced supersu with magisk. Similar process, but rather than flashing supersu from twrp, just download magisk.apk from github, rename to magisk.zip, and flash with twrp.

Upon reboot I still had to install the magisk apk manually, as the magisk app didn't show up. Once installed, I had to go through one more step in the magisk app to reflash it properly, using the direct install method.

Instructions to install twrp (google translated from the thread linked above):

Original post (Translated)​

A month ago I bought this tablet and these are the things I did to it and that can help you

Before that, thanks to:

lenovo-forums.ru - Where I got everything from

SevenMaxs - User of that forum, who made the TWRP

baikal0912 and Steaven - From that forum too, for posting the Roms for the tablet (5.1 and 6.0 respectively)

Note 1 from OP: If you already updated to the latest version without touching anything, you only need to do the first 2 points (if you want to)

Note 2: In case you have touched and cannot update, continue from the point that you have not done (bootloader, twrp or update)

1. Unlock Bootloader​

Activate developer options

For this you have to go to "Settings -> About the tablet". Once here, you have to touch several times on "Compilation number", until it says "You are already a programmer"

Enable debugging and unlock permissions

Go to "Developer Options" and check the boxes for "OEM Unlocking" and "USB debugging"

Connect tablet to your computer

Download file and unzip it

01. Bootloader

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

Run Unlock_Bootloader.bat

Note from Gramdalf: I was on linux, but was still able to do this - just look at the `.bat` file and enter the fastboot/adb commands as they are.

Review the tablet, as a code will appear and ask for permission to activate debugging, select 'Remember this computer's RSA key'

2. Install TWRP​

Connect tablet to PC

download file

02. TWRP

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

Install

-If it comes with Android 5 from the factory, apply TWRP 2.8.7.7.

-If it comes with Android 6, install TWRP 3.0.2.7 (a)

You only have to open the .bat that is in each folder.

Note from Gramdalf: Same thing, just enter the commands as they are in the .bat script, making sure that you are in the correct directory. The only difference with this is that with the `tools\fastboot -i 0x17ef flash recovery img\twrp.img` command, `-i` wasn't an available option - I was able to run it just fine without it. The recovery flashed correctly, but just keep in mind that I'm not sure if there are any lasting side effects that I am unaware of.

-If you have Android 5 and then update to Android 6, you have to install TWRP 2.8.7.7 and then you can flash 3.0.2.7 which is in the "TWRP 3.0.2.7 (b)" folder from the same TWRP (it's a zip )

Note from OP: TWRP says 850M, but it is compatible with it. There is a version from someone on XDA who tweaked a few things for the 850F, but I haven't tested it.

Note from Gramdalf: I didn't do the following part in my case, but it's there just in case you want it

3. Firmware​

Android 5.1

YT3-850F_USR_S000025_1510160911_Q1241_ROW_factory_update

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

Android 6

YT3-850F_000109_161226_ROW_otafull

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

Just go into TWRP and flash.

Note from OP: When upgrading from 5 to 6, the bootloader is locked again and TWRP is removed, you need to do step 1 and 2 again.

Root and Xposed

Enter TWRP

Flash SuperSU

Restart

Check that it is rooted

Enter TWRP

Flash Xposed

Restart

Install the Xposed APK

Verify that it has been installed correctly

04. Programas

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com