The instructions are fair enough, HOWEVER -
If you followed those instructions exactly then you got recovery from here -
http://htconeroot.com/cwmtwrp-recoveries/
And that's where the guide breaks down, they have no business hosting older recoveries. CWM recovery is NOT a valid choice here, it's been pretty much abandoned since shortly after the phone came out.
You want to get the latest recovery right from the source -
http://teamw.in/devices/htconem8gsm.html
Specifically (as of today, others reading this in the future need to check from the link above) -
https://dl.twrp.me/m8/twrp-2.8.6.1-m8.img.html
Place into your fastboot folder, put the phone into FASTBOOT USB mode and -
fastboot flash recovery twrp-2.8.6.1-m8.img
Most unfortunately, they took the big shortcut and jumped right to flashing after installing recovery - and that's wrong, it's essential to have a nandroid backup of your stock system before proceeding to flash anything.

Hopefully you've rooted before and caught the mistake.
They also have no business handing out old versions of SuperSU. Bookmark this page -
http://forum.xda-developers.com/showthread.php?t=1538053
Always get SuperSU from the source.
If you acquired the rom from a listing here, at XDA, or from a developer site with a support thread at XDA then your bootlooping is probably caused by a bad kernel flash. Unzip the rom on your pc, extract the boot.img file, move it to fastboot folder and with the phone in FASTBOOT USB mode -
fastboot flash boot boot.img
If you got the rom from anywhere else (especially if it's a discontinued Skydragon GPE rom) then DON'T flash the boot image, stop and tell me what you got.
Keep me posted, ask questions if you're unsure or if I've been unclear ok.