This is for pretty much ANY Android phone, and is a pretty old trick.

You can use most types of sound-files, using mostly MP3/OGG/FLAC  myself.

This is done on a regular EU One M8 running 5.0.1/Sense 6.

It’s pretty easy and straightforward:

• connect phone to computer (shown on windows 8 here), open the storage. Memory card if you got one of those in your phone.
• Choose what you want, you don’t have to create all. If you just want custom alarms, just create the alarms folder:
  • create folders notifications, alarms and ringtones as separate folders.
  • [shown as gallery] Create a folder called Media and in that create a folder called Audio, and under that create alarms, notifications and ringtones
• Copy the sounds you want to use into the folder of choice.
• Done!

Done right they should show up where you select ringtone. Sometimes you have to restart.

Sounds? you’ve got some HERE