Hey, this post is a bit old, but for anyone still wondering, you can actually already control the sprite resolver component really easily with Playmaker (took me forever to figure out though haha).
You need to drag the object's "Sprite Resolver (Experimental)" component into a state, then select "Call Method," then select "void SetCategoryAndLabel (string, string). After that, it's just a matter of typing in the category and label of the sprite you want to switch to.
Just a quick tip as well:
If you have meshes with bones, any sprites/meshes being swapped need to have identical bone hierarchies (they don't need to have weights on all of the bones, but they need to have the same bones assigned in the "Skinning Editor" tab of the Sprite Editor with the exact same order.
Hopefully that helps someone.