Sample code for creating runtime Spine ScriptableObjects.

RuntimeAssets.cs

using UnityEngine;
using System.Collections.Generic;

namespace Spine.Unity {
	public static class RuntimeAssets {

		public static AtlasAsset CreateAtlasAsset (TextAsset atlasText, Material[] materials, bool initialize) {
			AtlasAsset atlasAsset = ScriptableObject.CreateInstance<AtlasAsset>();
			atlasAsset.Reset();
			atlasAsset.atlasFile = atlasText;
			atlasAsset.materials = materials;

			if (initialize)
				atlasAsset.GetAtlas();

			return atlasAsset;
		}

		// Only providing the textures is slower because it has to search for atlas page matches.
		public static AtlasAsset CreateAtlasAsset (TextAsset atlasText, Texture2D[] textures, Shader shader, bool initialize) {

			if (shader == null)
				shader = Shader.Find("Spine/Skeleton");

			// Get atlas page names.
			string atlasString = atlasText.text;
			atlasString = atlasString.Replace("\r", "");
			string[] atlasLines = atlasString.Split('\n');
			var pages = new List<string>();
			for (int i = 0; i < atlasLines.Length - 1; i++) {
				if (atlasLines[i].Trim().Length == 0)
					pages.Add(atlasLines[i + 1].Trim().Replace(".png", ""));
			}

			// Populate Materials[] by matching texture names with page names.
			var materials = new Material[pages.Count];
			for (int i = 0, n = pages.Count; i < n; i++) {
				Material mat = null;

				// Search for a match.
				string pageName = pages[i];
				for (int j = 0, m = textures.Length; j < m; j++) {
					if (string.Equals(pageName, textures[j].name, System.StringComparison.OrdinalIgnoreCase)) {
						// Match found.
						mat = new Material(shader);
						mat.mainTexture = textures[j];
						break;
					}
				}

				if (mat != null)
					materials[i] = mat;
				else
					throw new System.ArgumentException("Could not find matching atlas page in the texture array.");
					
			}

			// Create AtlasAsset normally
			return CreateAtlasAsset(atlasText, materials, initialize);
		}

		public static SkeletonDataAsset CreateSkeletonDataAsset (TextAsset skeletonDataFile, AtlasAsset atlasAsset, bool initialize, float scale = 0.01f) {
			return CreateSkeletonDataAsset(skeletonDataFile, new [] {atlasAsset}, initialize, scale);
		}

		public static SkeletonDataAsset CreateSkeletonDataAsset (TextAsset skeletonDataFile, AtlasAsset[] atlasAssets, bool initialize, float scale = 0.01f) {
			SkeletonDataAsset skeletonDataAsset = ScriptableObject.CreateInstance<SkeletonDataAsset>();
			skeletonDataAsset.Reset();
			skeletonDataAsset.skeletonJSON = skeletonDataFile;
			skeletonDataAsset.atlasAssets = atlasAssets;
			skeletonDataAsset.scale = scale;

			// pre-patch workaround
			skeletonDataAsset.fromAnimation = new string[0];
			skeletonDataAsset.toAnimation = new string[0];

			if (initialize)
				skeletonDataAsset.GetSkeletonData(true);

			return skeletonDataAsset;
		}

	}
}

RuntimeSpawn.cs

using UnityEngine;
using System.Collections;
using Spine.Unity;

public class RuntimeSpawn : MonoBehaviour {

	public float spawnAfterSeconds = 2f;
	public TextAsset skeletonDataFile;
	public TextAsset atlasText;
	public Shader shader;
	public Texture2D[] textures;

	IEnumerator Start () {
		yield return new WaitForSeconds(spawnAfterSeconds);

		// Create runtime assets.
		var atlasAsset = RuntimeAssets.CreateAtlasAsset(atlasText, textures, shader, true);
		var skeletonDataAsset = RuntimeAssets.CreateSkeletonDataAsset(skeletonDataFile, atlasAsset, true);

		// Use them to instantiate a SkeletonAnimation.
		SkeletonAnimation skeletonAnimation = SkeletonAnimation.NewSkeletonAnimationGameObject(skeletonDataAsset);

		// Enjoy as is.
		skeletonAnimation.Initialize(false);
		skeletonAnimation.state.SetAnimation(0, "walk", true);
	}

}