The following are a copy of the root instructions originally posted by forum member djrbliss, Dan Rosenberg on his blog located here.  I am copying them here for convenience.  Before rooting your ThinkPad Tablet keep in mind that there is always risk involved with tampering with your Thinkpad Tablet's operating system and that risk and any possibly negative outcome or harm to your tablet is purely taken on by you.  With that said, here are the instructions and appropriate script/links for rooting the ThinkPad Tablet as taken from Dan's blog.

Rooting the Thinkpad Tablet

Another day, another Android root. Let’s just skip the details this time and let Lenovo figure it out for themselves. The following root package only works on Windows. I feel like a Linux traitor right now, but 99% of the people using this run Windows, and if you run Linux, just peek at the batch script and perform the steps manually.


Instructions

1. Make sure you have the latest ADB drivers installed on your PC, and that your device is in USB Debugging mode. More detailed instructions for this are available here.
2. Download the root exploit here.
3. Make sure your Thinkpad is connected to your PC via USB, is turned on, has the screen unlocked, and is connected to a wifi network.
4. Extract the entire zipfile, and run “run.bat”. Follow any directions given in the command prompt closely, and ignore any activity on the Thinkpad itself.

Enjoy!

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Unrooting the ThinkPad Tablet

The following 'unroot' instructions were posted by forum member twospirits:

For those that need to unroot (for example: having to take the tablet back to Lenovo for warranty work) the steps are as follows:
All credit goes to djrbliss (thanks Dan)

Instructions

1. Follow instructions to set up ADB.

2-Run "adb shell" from a command prompt.

3-In the ADB shell, type the following commands:

su
(this will cause a prompt to come up on the phone asking you to grant root permissions, accept this)

Then, back in ADB shell:
mount -o rw,remount /dev/block/system /system
rm /system/app/Superuser.apk
rm /system/xbin/su
rm /system/bin/su

Then you can exit and you're unrooted. Magic. 

I keep getting this error

Sent from my Galaxy Nexus using Tapatalk

I got those as well, keep following the prompt and press the key to reboot, you will get to root sucessful. Then run root check basic to verify.

:with homer voice: dooohhhh

Rooted with no errors under Windows.
Currently creating a backup with Titanium Backup before I start playing around.

Having a strange issue. Tried to go about rooting. Followed instructions, came upon the rebooting device within command prompt, tablet proceeded to reboot and it got to the screen that wants to choose MTP/USB/Low Charge only options. I ignored said options and pressed a key to continue the batch. The tablet at this point proceeded to reboot again. It is now in a state of constant rebooting.

I can see ADW start to load and then it simply reboots. I have also noticed something strange. ADB only seems to work when in MTP-mode. Is this the case for everyone? Not sure where to go from here.

Any suggestions?

Thanks in advance.

Windows 7 Pro 64bit. Yes, Android Phone shows up in windows, but ONLY if I choose MTP from the on-screen selection. I assume most of you know what that screen is. It is the dialog box that pops up when plugging the device into your computer.

TPT displays following pop-up;

PC Connection Detected.
Low-charge only...etc
USB Mount -> must have sdcard inserted in order for this to be an option, otherwise greyed out
Transfer Files, MTP-mode (Media Transfer Protocol) -> I believe that is correct.

Anyway, is that normal behavior for TPT and ADB to perform?

I did some trial and error with djrbliss and he figured out why it was rebooting constantly. We both had to run and haven't attempted anything thus far.

I have a feeling my ADB driver may be screwed up. I've connected many devices to my computer in order to have adb/fastboot access and am not sure how all the different drivers stack up with respect to Windows and said device. I assume Windows can tell the difference between Android devices and load the appropriate driver, but I also assume that this is too much to ask

Anyway, just an update.

EDIT: Oh by the way, I was not able to install the ADB driver until I didn't tapped on anything on my TPT when prompted.  When I tapped on MTP, the drivers could not be installed.  But when I said "Cancel", and updated the driver, then the adb installed properly.  But I'm trying to run some commands on cmd, but I'm not getting thru (just to test that the adv driver was installed properly).  When I type adb devices it tells me that "adb" was not recognized as command.

While holding shift and right clicking on the directory of Thinkpad_Root_Windows and select Open Command Prompt Here.

Now adb devices should work properly if the driver is installed. And you can proceed from there.

Cheers.

Do you have a PIN, lock pattern, or password. If so enter it when you connect the tablet to the computer or better just remove any screen lock before starting and enable it again after rooting.