First off, thank you very much for posting this. I have implemented it to our system and it works great. Second I just wanted to share my experience for those of you who are looking to update to 9 or 10. We are using 10 with these scripts and it works great, you just need to do a few additional steps to get it going.
1. Install as stated by the OP with Version 8.
2. Once you have tested and made sure the ID and Password are importing to Labtech correctly move on to step 3
3. I customized the Version 10 exe on the Teamviewer Website and uploaded it to the Labtech server. Create a script that downloads the exe into the same dir as the install script and runs is silent with no password switch. This will update Version 8 without changing the password.
4. Update your engineers version to 10 as well.
Once you follow these steps you will have Version 10 installed and working just as well as 8 and you don't have to worry about autoupdate working or not working. Let me know if you have any questions.