@zeromuppet: about the not being able to choose. I have a similar problem with the TOS costume I got from my preorder package. It's in the list, and when I make a new toon I can choose it, but when editing an existing character the choice doesn't "stick".
Just as a note, this will not be in your C-Store. Try to make a new character, or simply take your current character to the tailor. In the Uniform menu, you will see "Mirror - Terran" under tops. If you select it, you will also have a Mirror - Terran combadge option. Select the cutoff pants and leather boots, and you will have a Belts dropdown menu with Sash - Terran.
All of this is currently only available for men. There's apparently some issue with the skirts, and female characters cannot access Mirror uniforms yet.