Follow [[http://wiki.cyanogenmod.org/w/Install_CM_for_m8]]

  - Unlocked bootloader using http://htcdev.com/bootloader/.
  - Flashed TWRP ([[https://twrp.me/devices/htconem8gsm.html]]).
  - Took a full backup with TWRP.
  - Powered off
  - Move MicroSD card to PC
    - copy TWRP backup to PC
    - copy CyanogenMod to SD card
  - Re-insert MicroSD card
  - Boot to recovery and install CyanogenMod 11 from MicroSD card
  - After a test call had a bad audio issue. It sounded like the speaker was cracking and could get damaged (http://forum.cyanogenmod.org/topic/102031-cm11-nightly-20141116-audio-issue/page__st__20). Immediately powered off and installed CM12.