Hi!
I know that there are people out there who are still having issues, and after having many, many, MANY problems installing the driver from Huawei, I FINALLY got it working!
So here are the steps I followed, and if it helps anyone, then my good deed is done! 😍 Thank you, also, to the various people I have used information on in this thread, it all helped in some way....especially Eau Rouge!
1. Start computer in Recovery Mod (Cmd + R) during startup. Based on my experience, you should be connected to the internet (via cable) if possible.
2. After the system has started, go to the Menu bar at the top, and click on Utilities, and then Terminal in that dropdown menu.
3. Enter csrutil disable into Terminal and press Enter.
4. Restart the laptop, and download both these drivers:
http://download-c.huawei.com/download/downloadCenter?downloadId=54976&version=17 4669&siteCode=worldwide
http://download-c.huawei.com/download/downloadCenter?downloadId=54978&version=17 4677&siteCode=worldwide
Once downloaded, I then put the zip files into a folder in 'Applications' named Drivers. I was able to open and install the second download with The Archiver app, but it will not open the first download listed here - and I think this was the problem I kept running into. I finally tried opening the first download with DiskImageMounter, and that finally worked (I could hear the angels sing!). Once installed, this driver is a Mobile Partner driver, but it worked just fine with my Virgin Australia mobile USB modem in Australia. No need to install the driver on your USB modem.
However, I have yet to try it yet with re-enabling csrutil, but I'm just soooooo relieved to have internet back!!!
Here are the steps I will follow to re-enable csrutil...
5. Restart computer again in recovery mode, go to Terminal, and enter csrutil enable and press Enter.
6. Restart again and with some blind luck, all will be good again!
I hope this helps those people who are having issues with not being able to install the driver, it was only by pure chance and desperation that I found the solution that finally unlocked it all for me...Good luck! 🙂