Okay, I found a workaround for now!
let renderer = (this.actor.spriteRenderer as any).__inner; renderer.material.map = renderer.asset.textures["blue"]; renderer.material.needsUpdate = true;
Where "blue" should be the name of your map. Also note this probably won't work if your maps doesn't have the same size.
EDIT: spriteRenderer should be modelRenderer if you are working with a model. I didn't read your question carefully enough, sorry '^^