The best way to make a supremecey map would be to RMS, or random map script it. I personally know very little about how to do this, but there are many guides that you can read.
If you want to use triggers (not recomended) to choose where the TC is, set 8 or so cinamatic blocks in a ring with a hawk that starts in the middle. The hawk will go in random directions and whichever way it goes you can have that TC be the one that appears. (I saw that on some previous post a LONG time ago. don't know if it works but it sounds lagit.) If you don't know how to use triggers, when then your SOL.
If you give a man a match, he will be warm for an hour. If you set a man on fire, he will be warm for the rest of his life.