I finished the first version of my Mixamo Rig Converter script.

With this script, you will be able to download anything you want off Mixamo and turn it into an animateable rig.
It will create controls to animate the rig. The existing animation will then be transferred over to these controls.
Display and Animation layers will be automatically generated, for easy organization.
The created animation layer is additive with all controls added to it, so you will be able to start animating right away.

You can check the Joint Orientation of the rig with the first 2 buttons.

Next, you can decide how big the NURBS circles will be for your controls.
Don’t forget to click set. You can create some test sizes beforehand and delete them all at once when you find the right size.

You can set the time range of what parts of the animation you want.
The frequency is how often they will set a keyframe.

When you have set everything, click the bottom button and have fun with your new rig.