Setting Avatar to Humanoid at runtime

Hello, I've been coding in Unity for a while now, but I am a newb to the forums. I am attempting, without much success so far, to build an FBX uploader for runtime use. The main reason is so that users can build humanoid avatars and upload them to use. In order to integrate them into the game I need to program functionality that allows me to write generic scripts for the avatars. One thing that would make my life infinitely easier would be able to set the uploaded avatars to humanoid and use the SetLookAtPosition function. The reference says : Description Gets/Sets the current Avatar.

Changing the avatar at runtime is not fully supported. Use it at your own risk.

Which makes me think that it's possible to access it. I was hoping I could do something like "anim.avatar.rig = humanoid;" Any help would be awesome! Thanks in advance!