Where/How can I get/implement a Sky model?

I have heard talk about sky models and so I searched around for one. "No results found"...

I search a number of sites, same response.

Please, where can I get one, and how do you add it in?

There must be a few available for download, I've seen many screenshots from different users that used the same custom skybox. Try searching at the hive workshop. If you did, then I'm sorry, I don't know.
You add it in just like any custom model and you apply it via an environment trigger that sets the sky to whatever model you chose.

the sky model can be used for space with alphaed tiles right?

I guess so, but it'll have to be a sky box with the bottom plane painted too. Wc3 ones have the same texture on all 4 side planes and no texture on the top and bottom ones, it just stretches that texture over those planes.

Stretched over the top, yes, but they actually have no bottoms at all.

And let's face it, when you're playing with the alpha tile, the bottom is where it's at.