Here is a more clear, step-by-step guide.
1) Flash the US Unlocked firmware, modified for Verizon.
1a) Here is the one I personally used, that is already modified.
1b) CAUTION - Flashing this did wipe my internal, so back up everything! Back up everything either way.. even if you're just reading this.
1c) How to flash?
2) After you issue the 'fastboot reboot' command you will most likely get stuck on the hTC splash screen as the modified firmware wiped everything, including your system (ROM). If it didn't, not a problem - reboot the device to download mode and continue onto step 3.
2a) Hold Vol
+ Vol
- and Power buttons until the phone reboots. Keep holding Vol
- while letting go of the other buttons. This will bring you to download mode.
3) Now flash the Official Verizon 1.85.605.8 RUU from dottat. Putting you back to a full Verizon variant device. Thread
found here.
3a) Let the RUU boot fully up to the stock ROM after the installation finishes.
3b) Make sure to have the AOSP ROM of your choice either on SD-Card or move it now onto the Internal storage.
4) Set your device back to your liking. Splash screen, etc.. but also now you flash
TWRP.
4a) If you use multirom, I would still first finish these steps, then you can flash the multirom TWRP and zip. (I am using multirom successfully with both Stock Verizon 1.85.605.8 ROM as primary and CM, AOKP and Resurrection Remix AOSP ROMs as secondaries while being fully Verizon variant device, thanks to this process)
5) Boot to TWRP. Do a full wipe and flash your AOSP ROM.
5a) Note - Most the AOSP ROMs (possibly all that are out?) will boot to the boot animation and then go to a black screen for a minute or so, don't freak. This is normal behavior and will resume back to the boot animation.
6) Enjoy! Be baffled like myself as to why this worked. Also hit thanks button if this helped you.