In the other threads about macOS Sierra, I was among the people loudly complaining that this should have been tested and fixed earlier, blah blah blah...
Much better than whining is trying to help, so here's my contribution which I think fixes the problem properly, until Access can release a nicely packaged fix.
Much of the credit goes to "skittb123" for finding out that the issue had to do with SIP and offering an initial workaround, which put me on the right track !
A bit of searching on the Apple developer forums gives the root cause of the problem that Access / Ploytec will have to fix : https://forums.developer.apple.com/thread/50380
In the meantime, we can do a quick fix ourselves in a few minutes.
The following procedure fixes the driver itself, it is a much cleaner solution than disabling SIP on the entire Mac (which can leave it more vulnerable to malware)
Disclaimer : I have no link with Access (other than being a faithful customer) and this is done at your own risk. There is not much risk, though
If you have a very old (probably before 2009, check here: https://support.apple.com/en-us/HT201948) 32-bit Mac, then you'll need to replace "x86_64" in step 5 below with "i386" :
1. Install the Virus TI Installer 184.108.40.206
2. Open the Terminal app
3. Copy/paste the following commands exactly as shown and type return after each. Enter your Mac password when you're asked to.
4. First let's backup the original driver file, just in case :
5. Then let's fix it by keeping only the 64bit part of the driver :
6. That's it ! Plug-in your Virus TI and enjoy.
7. If for some reason you want to revert to the original state, either reinstall the Virus driver, or do this to restore from our earlier backup :
(Ironically, not tested with my actual Virus TI yet since I'm away from home, but I can confirm that the driver loads after this procedure and it should be all that's needed !)