You can take their tubes though... Tubes are a "neutral" thing on the map.
(For example, once in La Corrida I killed the base in the center... then I went there, and built a cc, etc and the tubes hooked them up fine.)
Once the sheets.vol is figured out (if ever? I'm so busy right now) we could possibly make buildings "reprogrammable" with spiders.
(I had a thought just now: It will be possible to make separate tech trees and everything for missions, since in the DLL file it refers to a .TXT just as it refers to the .map.. All you'd have to do, is make a new TXT file, "encode" it, then put it in the folder of the game / or in sheets.vol itself.)