Well here it is Jan 24, 2016 and like others, I stumbled here to solve the same problem! I know just enough to throw a monkey wrench in the works if I were to try using terminal, so I happily went over to wireload.net to download GUU, only to find that they no longer support or update it 🙁
Searched a little further…

Ironically, even google’s links to its own support pages for GSU are dead, eg.,
this link:
https://support.google.com/installer/bin/answer.py?hl=en-GB&answer=147176
on:
https://support.google.com/search?q=Google+Software+Update&vid=1-635892917286438784-2802967168
and:
https://support.google.com/installer/answer/100386
(uninstall instructions)

Google must have deleted them after Feb2014, as they were also referenced in this article re: disabling GSU on OSX Mavericks:
http://www.labnol.org/internet/google-software-update-control-computer/28408/

This article seems to provide similar advice (current up to Nov2014):
http://applehelpwriter.com/2014/07/13/how-to-remove-googles-secret-update-software-from-your-mac/

And I found this, from Aug2015:
http://www.macobserver.com/tmo/article/how-manage-the-secret-software-that-google-chrome-installs-on-your-mac

Alas, I don’t dare try it… Raam, I don’t suppose (in all your spare time) you’d be interested in tweaking the “old” GUU so it’d work with the current GSU and OSX Mountain Lion…? Hey, it can’t hurt to ask, right? 😉

ps – I think its been hugely generous of you checking in and responding here for the last SEVEN YEARS!!