Scenario editor help needed- how do I make a control point?

I'm new to scenario editor, but I have an idea. I want to make a map where there's a central control point that can change ownership. The thing is that I have no idea how to make it work. Here's what I want it to do:

-Unit is in proximity to flag.
-Timer starts, 10 seconds. Unit must stay alive for capture to complete.
-Flag changes ownership, generates 500 score for every 30 seconds held.

Is this remotely possible within the bounds of the scenario editor or am I being too ambitious? I'm not even sure how to make a basic trigger/cause/effect so the answer is "probably..."