You control it through code just like SkeletonAnimation, through the AnimationState API.
var skeletonGraphic = GetComponent<SkeletonGraphic>();
Spine.AnimationState state = skeletonGraphic.AnimationState;
state.SetAnimation(0, "my looping animation", true);
If you need it to interface with Unity AnimationClips and Unity Animation Events, you need to write a small component to do this on your behalf, and write specifically how you want it to behave and how you want to use it.
The string AnimationName interface on SkeletonAnimation was not ideal for everyone, especially for UI, so it wasn't replicated in SkeletonGraphic.
