1. Download the Seven-Eighter app from Windows Phone Hacker at windowsphonehacker DOT com [I can't load links yet, so excuse the typing]
It will be zipped, so just "extract all" to unzip it.
2. You will also need to download the Wp7 Updater Tool from the same website. That will be a .rar file. Just get the right software to open and install the Wp7 Tool on your PC.
3. Now that Wp7 Updater Tool is installed on your PC, go back to the Seven-Eighter app. With your Titan II plugged in to your pc via usb and it's on, run the 7.8 app [SevenEighter.exe]. FYI, in the Seven-Eighter app folder, you'll have a "run" app and two folders. You need the "run" app. Just ignore the folders.
4. You'll be prompted to choose your languages. Choose them ALL! This is key. You need all of them, not just the English one. So, check every box, otherwise the update won't take. [you have to check each one at a time]
5. The progress box will begin and run through this cycle: Downloading Files... Transferring Files... Installing... Restarting Phone. It will do this for each of the updates you need to get to 7.8. My phone took 4 updates I believe since I never got Tango. You don't need to re-run it each time, it will just keep going automatically until you get to 7.8. Just don't unplug the phone and just sit back and watch the show. You'll know you've reached 7.8 when the progress bar gives you a pop-up that says, "Congratulations. You're Done!"
And that's it. Good Luck.