Chaning out the Skin on a model

[Titanhex]

I thought I saw, a long time ago, a method of changing through skins on a unit or model. I thought this could be a very useful feature, but am not sure how it was done.

So, how can you swap out the skin used on a model in game? (That is, while the game is being played.) I believe it was done through JASS coding.