So far, the only method I've had ANY success with for stopping Chrome auto-update, is to delete it's "Update" folder.
See here: http://community.smartbear.com/t5/Functional-Web-Testing/Chrome-v-44/m-p/102713#U102713
But even that is no longer working in my VM. Although it has held up on my physical PC (just checked). No idea why it's holding on one and not the other.
And if you get an offline installer, be careful when you install with it. The first thing it does when the install completes is goes to the "About" page and looks for updates. So kill Chrome as soon as it starts after the offline installer completes.
I'm also curious why you want to go back to 45 from 46? My VM is running TC11.11 and works just as well with Chrome v46 as it did with v45?