Sorry for the late reply.

Do you mean when you are inside the Death Star looking out of the hangar? Due to the way the Source engine works with skyboxes it's not very easy to make it so a single map has more than one skybox. Yes it would theoretically possible, but it would be a pain in the ass to make. So maybe only if there's a really good reason to change the skybox on there.
Did you have anything specific in mind?

Haha its fine now man I don't even remember what I needed to do it was so long ago. It wasn't anything important, I might have just wanted to put a star destroyer there or something.