welcome to Away Miguel.
You arrive at some moment where the doc and examples are not reflecting at all the latest trunk code. As we are in the process of releasing a new version.
On the animation side, lots of things have changed and we will publish more info on this soon.
Here's a snippet that uses the latest trunk that should help you get your anim running...
once the md2 is loaded (reffer to doc or search this group for loading procedures)
private function md2IsLoaded(e:Loader3DEvent) : void
var mesh:Mesh = _loader.handle as Mesh;
var animdata:AnimationLibrary = mesh.animationLibrary;
var myAnim:VertexAnimator = animdata.getAnimation("walk").animator as VertexAnimator;
myAnim.delay = 0;
myAnim.loop = true;
myAnim.fps = 5;
myAnim.interpolate = true;
Note: Transition class is missing in this update but will be reintroduced very soon.