You will have to use Google Search to download an older version of the software. Access Google Results and then download a version from Old Apps. After the browser has been installed, copy the below code to Notepad and save the file as disableupdate.reg or whatever you like, but keep the REG extension. Merge the settings to the registry and that's it. Chrome won't automatically update anymore.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Update]
"Update{8A69D345-D564-463C-AFF1-A69D9E530F96}"=dword:00000000
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Policies\Google\Update]
"Update{8A69D345-D564-463C-AFF1-A69D9E530F96}"=dword:00000000