el desarrollador del nexus root toolkit a colgado esto en su wed:
Yes, I am aware that this isn’t working on 4.2.2 right now. This will be fixed in v1.6.3 which will be released ASAP (within a few days or sooner if possible). As a temporary fix you can replace the old adb/fastboot/dll files in the toolkits /data directory with the new ones: new_adb_and_fastboot.zip just download that zip and extract/unzip its contents into the toolkits /data directory and agree to overwrite those files, then proceed to use “Any Build” mode to perform subsequent operations like rooting. Again, this is just a temporary fix for those who are impatient.
De todas formas voy a seguir intentandolo