Hi,
ngui is a regular component and gameobject. Can you animate a cube using itween? when you have the proper behavior there, try then with a ngui button.
Also, have you studied ngui samples, Ngui features a very powerful tweening engine all tie within Ngui events and all, so I think you may actually trying to implement something that is already there for you.
What do you mean by "it meshes up"
bye,
Jean