this is the BIG TextureAtlas.
basically what it does is the same as the normal TextureAtlas. the difference is that with this class you can give 3 textures and 3 xml files. i ran into this problem at work trying to animate 70 frames 3Dmax rendered 2d sprites cause Starling only supports 2024x2024 and smaller!
what you do is.. you create a sprite sheet with xml until the 2024x2024 preview window is full and create another sprite sheet and xml for the remaining frames of your animation. (note: this also works for 4 sprite sheets with xml files).
Here is a example.
[Embed(source = "../example_0.xml", mimeType = "application/octet-stream")]
private var AtlasXML1:Class;
[Embed(source = "../example_1.xml", mimeType = "application/octet-stream")]
private var AtlasXML2:Class;
[Embed(source = "../example_0.png")]
private var AtlasTexture1:Class;
[Embed(source = "../example_1.png")]
private var AtlasTexture2:Class;
var tex1:Texture = Texture.fromBitmap(new AtlasTexture1());
var tex2:Texture = Texture.fromBitmap(new AtlasTexture2());
var xml1:XML = XML(new AtlasXML1());
var xml2:XML = XML(new AtlasXML2());
var atlas:TextureAtlas = new BigTextureAtlas([tex1,tex2],[xml1,xml2]);
var mc:MovieClip = new MovieClip(atlas.getTextures());
these are the links for download. if there are any questions please ask me.
EDIT: updated links!