Ok, incase anyone else was wondering how to do this heres what I did. Hopefully this will help you guys.
From a totally stock AT&T HTC One with 4.4.2 HBOOT 1.56:
*****THIS WILL WIPE DATA. BACKUP ANYTHING YOU WANT TO KEEP*****
1. Unlock Bootloader via htcdev.
2. Flash TWRP (I used 220.127.116.11)
3. Install SuperSU on reboot of TWRP
4. Enable developer options.
5. Enable USB Debugging.
6. DISABLE FAST BOOT
7. Plug Phone into computer.
8. Do "adb devices" to make sure its found.
9. Accept the RSA Key. ( Always accept if you want)
10. Run Firewater.
11. On the enter "su" step, make sure you WAIT until the SuperSU message comes up, then grant it. ( You may have to type "su" 2-3 for it to ask )
12. Continue with Firewater
This is what I did and it worked on the first try! ( Actually 2nd, I got too eager and accidentally unlocked my device when it was working. Don't worry, it will just tell you try again and DONT TOUCH THE DEVICE )
P.S. Ask firewater support if you need help, these are just instructions I did to do it.
Hopefully this helped!