I've never made one of these so it strictly conceptual. Imagine this: get a 4x4 that is say 5' or 6' tall and stand it on its end and screw it to the studs in the wall (this just keeps it from tipping over but should prolly be some decent size screws. On the other side of the room do the same thing. Then to borrow from the turtlelady/turtledog stands secure a compression pole to the top of the 4x4, whether you do that my cutting a U shape to accept the pole or some other means to hold it still is up to you. Now simply hang your hammock from the compression pole... Easy to put up and down and doesn't take up the whole room. Again this is purely theoretical but I can't see why it wouldn't work. You could use THESE poles as mentioned in the turtledog stand thread.
Red, I am in the process of doing something quite similar to what you describe, but going full wall height to allow for more adjustability for different hammocks, where the point of hanging will be on the verticals and the compression piece will only keep the ends from pulling in. When finished and tried I will post results.