Updated 11-17-12: Now that we have a stable CWMR image thanks to damien667 this procedure should be a lot less risky and less stressful!
This is confirmed working but due to the procedure involved is risky! The standard XDA disclaimer applies: I take no responsibility for bricked devices due to the following rooting procedure, no warranty express or implied is given, I will not be held responsible if you mess up your tablet by following this procedure!
You must unlock the bootloader before performing this procedure!
Credits: Kidgoo for testing and coming up with the method, thanks to damien667 for the fixed CWM images, and Chainfire for the SuperSu zip and binaries!
Before you begin make sure you read and reread the procedure and fully understand the directions.
1. Download the CWM-SuperSU-v0.98.zip
2. Download damien667's fixed CWMR 220.127.116.11 touch version of from here
3. Connect the Nexus 10 to your computer
4. Flash the CWMR image you downloaded in step 2 using fastboot
fastboot flash recovery /path/to/<recovery>.img fastboot reboot
6. Select CWM-SuperSU-v0.98.zip that was downloaded in step 1
7. Let CWM-SuperSU-v0.98.zip install
8. Select "Reboot System"
9. Enjoy your rooted Nexus 10 !
To keep your custom recovery installed permanently and not get overwritten by the stock recovery when your reboot your tablet delete the following: