Here's how to get Executor in skirmish
Maybe this should go in the mod forum, but since FoC is new, I might as well put it here--especially since I'm not offering anything to download.
First, extract the XML directory from Config.meg as normal. Then go to starbases.xml and open it up with notepad. Use ctrl+F and search for 'Executor' (without the quotes). You'll find a line that says "Uncomment this line to use Executor in multiplayer."
Well, do just that, and you'll be able to use the ship in skirmish mode.